MANUAL  OF  CHEMISTRY ; 

CONTAINING 

A  CONDENSED  VIEW  OF  THE  PRESENT  STATE  OF  THE 

SCIENCE,   WITH  COPIOUS  REFERENCES  TO   MORE 

EXTENSIVE  TREATISES,  ORIGINAL  PAPERS,  &c. 


INTENDED  AS   A  TEXT-BOOK  FOR  MEDICAL  SCHOOLS,   COLLEGES   AND 
ACADEMIES. 


Br  LEWIS  C.  BECK,  M.  D. 

PROFESSOR  OF  CHEMISTRY  AND  BOTANY  IN  THE  UNIVERSITY  OF  THE  CITY  OF 
NEW-YORK,  AND  IN  RUTGERS  COLLEGE,  NEW  JERSEY  ;— -MEMBER  OF  THE  ROYAL 
PHYSICAL  SOCIETY  OF  EDINBURGH  ?  OF  THE  LINNvEAN  SOCIETY  OF  PARIS;  OF 
THE  NATURAL  HISTORY  SOCIETY  OF  MONTREAL;  OF  THE  PHILADELPHIA  ACAD- 
EMY OF  NATURAL  SCIENCES  ;  OF  THE  NEW-YORK  LYCEUM;  OF  THK  ALBANY 
INSTITUTE,  &C.  &C. 


SECOND   EDITION,     REVISED  AND  ENLARGED. 

MripMBBOb 
,\6RA* 
OF  THE  ^ 

UNIVERSITY 

OF 

isg^UFQRN^ 

ALBANY: 
PRINTED  AND  PUBLISHED  BY  E.  W.  $  C.   SKINNER, 

L  AND   SOLD   BY  THE   PRINCIPAL   BOOKSELLERS. 

M.DCCC.XXXIT 


Entered  according  to  'Act  of  Congress,  in  the  year  1831,  by  LEWIS  C. 
BECK,  in  the  ClerVs  Office  of  the  District  Court  for  the  Nortliern  Dis- 
trict of  the  State  of  New-  York. 


TO 

T.  ROMEYN  BECK,  M.  D. 

PROFESSOR  OF  THE  INSTITUTES  OF  MEDICINE 
AND  MEDICAL  JURISPRUDENCE, 

IN    THE 

UNIVERSITY  OF  THE  STATE  OF  NEW-YORK,   $c.  fa 
THIS   VOLUME  IS  INSCRIBED, 

AS   A   SLIGHT   TRIBUTE    OF    RESPECT   FOR   HIS   SCIENTIFIC    ATTAINMENTS, 

AND   OF    GRATITUDE    FOR   THE    MANY   PROOFS    OF    KINDNESS 

WHICH   HAVE   BEEN   RECEIVED   FROM   HIM 

BY   HIS    BROTHER, 

THE  AUTHOR. 


PREFACE 

TO    THE    SECOND    EDITIOX. 


THE  adoption  of  this  work  as  a  Text  Book  in  several  of  our 
most  respectable  Institutions,  and  the  rapid  sale  of  a  large 
Edition,  are  gratifying  evidences  of  public  favour, — the  con- 
tinuance of  which  I  have  endeavoured  to  ensure  by  the  im- 
provements which  have  now  been  introduced. 

In  this  edition  I  have  adhered  to  the  original  plan  of  the 
work,  which  was  to  set  forth  in  a  concise  and  perspicuous 
manner  the  principal  facts  of  the  science  to  which  it  is  devot- 
ed ;  and  at  the  same  time  to  furnish  the  student  with  such 
references  to  other  works  and  memoirs  as  may  give  direction 
to  his  inquiries  in  cases  of  doubt  or  difficulty, 

In  the  revision  of  this  volume,  I  have  constantly  consulted 
the  latest  editions  of  the  elaborate  treatises  of  Berzelius,  The- 
nard,  Thomson  and  Henry ;  and  of  the  smaller,  though  not 
less  valuable  ones,  of  Brande  and  Turner.  I  should  state, 
however,  that  the  work  of  Dr.  Turner  has  been  used  more 
freely  than  any  other,  and  may  in  some  respects  be  considered 
the  basis  of  the  present  Manual. 

The  method  of  arranging  the  subjects  is  essentially  that  ori- 
ginally proposed  by  Professor  Brande ;  which  I  have  adopted 
from  the  conviction,  that  although  not  entirely  free  from  ob. 
jection,  it  is  upon  the  whole  more  easily  acquired  by  the  stu- 
dent than  any  which  to  my  knowledge,  has  hitherto  been  fol- 
lowed. 

In  the  description  of  individual  substances,  I  have  studied 
brevity  as  far  as  was  consistent,  and  have  employed  in  many 
instances  the  style  usually  pursued  in  Natural  History.  I 
have  in  general  omitted  descriptions  of  apparatus,  and  the 
more  delicate  manipulations,  as  these  would  have  increased 
the  size  of  the  book  beyond  the  limits  assigned  to  it.  This 
department,  moreover,  has  been  made  the  subject  of  a  separ- 
ate treatise  by  Mr.  Faraday,  and  will  probably  hereafter  hold 


VI  PREFACE. 

a  place  distinct  from  the  views  of  the  science  to  which  text 
books  must  now  be  confined. 

The  improvements  in  the  present  edition  consist  in  the  in- 
troduction of  many  interesting  facts  discovered  within  the  last 
three  years,  which  are  inserted  in  their  proper  places ; — the 
adoption  of  atomic  numbers,  founded  on  the  experiments  of 
Berzelius  and  Turner; — and  the  employment  of  symbols  to  de- 
note chemical  substances  and  their  compounds.  The  number 
of  references  has  also  been  increased  and  the  results  of  origi- 
nal investigations  have  in  several  cases  been  introduced. 

With  regard  to  the  atomic  weights  and  symbols  employed  in 
this  edition,  some  explanation  may  be  necessary.  It  is  well 
known  that  two  sets  of  chemical  equivalents  or  atomic  weights 
have  for  some  years  been  current  among  chemists.  The  one, 
founded  upon  what  appears  to  be  an  incorrect  hypothesis,  that 
the  atomic  weights  of  bodies  are  multiples  by  a  whole  number 
of  the  atomic  weight  of  hydrogen,  has  until  recently,  been  al- 
most exclusively  adopted  in  England  and  in  this  country 
The  other,  proposed  by  Berzelius,  and  founded  upon  numerous 
and  most  accurate  analyses,  has  been  sanctioned  by  the  Con- 
tinental Chemists,  and  is  now  beginning  to  be  employed  in  the 
English  chemical  treatises.  It  is  this  last  which  1  have  now 
adopted,  for  the  simple  reason  that  it  is  based  upon  experi- 
ment and  not  upon  hypothesis.  But  in  order  to  avoid  the  nu- 
merous and  inconvenient  decimals  of  Berzelius,  I  have  used 
the  numbers  given  by  Dr.  Turner,  in  the  Fourth  Edition  of  his 
"  Elements  of  Chemistry,'5  as  being  more  simple,  and  for  all 
ordinary  purposes  sufficiently  near  the  truth.  These  numbers 
the  author  states  to  be  founded  on  his  own  experiments  and  on 
those  of  Berzelius. 

Symbols  have  not  heretofore  found  much  favour  among  our 
chemists,  and  an  opinion  unfavourable  to  them  is  expressed 
in  this  work,  which  I  at  first  intended  to  carry  through  the 
press  without  introducing  them,  although  I  had  observed  that 
they  were  employed  by  several  English  chemists.  But  a  more 
attentive  examination  of  the  subject  induced  me  to  change  my 
plan  in  this  respect.  The  symbols  which  I  have  adopted  are 
placed  at  the  head  of  each  article,  so  that  their  meaning  will 
at  once  be  understood,  and  cannot  occasion  the  least  embar- 


PREFACE.  Vll 

rassment  to  the  student.  I  have,  moreover,  used  them  in  ac- 
cordance with  the  rules  of  algebra.  The  atomic  weight  of  each 
element  is  denoted  hy  the  first  letter  of  its  Latin  name,  and 
when  the  names  of  two  or  more  elements  begin  with  the  same 
letter,  the  distinction  is  drawn  by  adding  an  additional  letter. 
Thus,  B  is  the  symbol  for  Boron,  Ba  for  Barium.  When  bo- 
dies combine  atom  to  atom,  as  in  the  case  of  Protoxide  of  Chlo- 
rine, the  symbol  is  Cl+O  ;  but  when  more  than  one  atom  oi 
an  element  is  contained  in  a  compound,  a  figure  indicates  the 
number  of  atoms.  Thus,  4O-f  Cl  denotes  Peroxide  of  Chlo- 
rine, and  indicates  that  it  consists  of  4  atoms  of  Oxygen  com- 
bined with  I  atom  of  Chlorine.  Degrees  of  oxydation  are  some 
times  expressed  by  Berzelius  and  others  by  dots  placed  over 
the  symbol ;  but  in  order  to  avoid  confusion  I  have  uniformly 
adhered  to  the  plan  of  expressing  them  by  figures. 

In  those  cases  where  the  symbol  is  complex,  abbreviations 
are  sometimes   employed.     Thus,  Aq  for  water,  (Aqua)  and 
Ac  for  Acid,  will  be  occasionally  noticed  in  the  descriptions 
the  salts. 

It  only  remains  for  me  to  acknowledge  the  important  assist- 
ance which  I  have  received  from  my  brother,  Dr.  T.  Romeyrr 
Beck.  To  him  I  am  indebted  for  many  useful  suggestions  as 
well  with  regard  to  the  general  plan  of  the  work,  as  to  its  more 
minute  details.  By  the  use  of  his  manuscript  book  of  chemi- 
cal references,  the  labour  of  one  part  of  the  work  was  muck 
abridged.  The  entire  articles  on  the  action  and  tests  of  Arsenic, 
Corrosive  Sublimate,  and  Tartar  Emetic,  were  furnished  by 
him.  And  in  consequence  of  my  engagements  at  a  distance 
from  the  publishers,  he  has  rendered  me  an  equally  important 
service,  by  assuming  the  task  of  revising  and  correcting  the 
sheets  as  they  passed  through  the  press. 

UNIVERSITY  OF  THE  CITY  OF  NEW- YORK, 
December,  1834. 


CONTENTS. 


Page. 
DEFINITION  OF  CHEMISTRY.  ...  .13 

CHAPTER  I. 

ATTRACTION. 

SECTION     I.     Cohesion— Crystallization,  .  .  .14 

SECTION    II.     Affinity,        .....  22 

SECTION  III.    Of  the  proportions  in  which  bodies  combine.     Ato- 
mic theory,  .  .....        27 

CHAPTER  II. 

CALORIC    OR   HEAT. 

SECTION      I.  Nature  of  Caloric,            .               ...  35 

SECTION     II.  Communication  of  Caloric — Radiation.      Conduc- 
tion, ...  .  .  .  .  .36 

SECTION  III.  Distribution  of  Caloric,             ...  43 
SECTION  IV.  Effects  of  Caloric — Expansion,  Liquefaction,  Vapor- 
ization,          .......  46 

SECTION    V.  Specific  Caloric,             ....  59 

SECTION  VI.  Sources  of  Caloric,            ....  60 

CHAPTER  III. 

LIGHT,  .  .  .  .  .  .  65 

CHAPTER  IV. 

ELECTRICITY. — Galvanism, 70 

CHAPTER  V. 

MAGNETISM. — Electro- Magnetism.    Thermo-Electricity,         .         .     83 

CHAPTER  VI. 

ELECTRO-NEGATIVE    BODIES. 

General  Remarks,  explanation  of  the  Nomenclature,  &c.        .          96 


X  CONTENTS. 

Page. 

SECTION     I.     OXYGEN,  .....  98 

SECTION  II.  CHLORINE— Protoxide  of  Chlorine,  Peroxide  of  Chlo- 
rine, Chloric  Acid,  Perchloric  Acid, 

SECTION  III.     BROMINE — Bromic  Acid,  Chloride  of  Bromine,  104 

SECTION  IV.     IODINE— lodous  Acid,  lodic  Acid,  Chloriodic  Acid, 

Bromides  of  lodifie,  .....         106 

SECTION  V.     FLUORINE,          ... 

CHAPTER  VII. 

ELECTRO-POSITIVE    BODIES. 

SECTION  I.  HYDROGEN — Water,  Deutoxide  of  Hydrogen,  Muri- 
atic Acid,  Hydriodic  Acid.  Hydrobromic  Acid,  Hydrofluoric 
Acid,  .  .  '.  .  .  .  >im  110 

SECTION  II.  NITROGEN — Atmospheric  Air,  Protoxide  of  Nitrogen, 
Deutoxide  of  Nitrogen,  Hyponitrous  Acid,  Nitrous  Acid,  Ni- 
tric Acid,  Nitro- Muriatic  Acid,  Chloride  of  Nitrogen,  Iodide 
of  Nitrogen,  Ammonia,  Salts  of  Ammonia  and  the  foregoing 
Acids,  .  *'.  .  ,  .  •  .  .  .123 

SECTION  III.  SULPHUR — Hyposulphurous  Acid,  Sulphurous  Acid, 
Hyposulphuric  Acid,  Sulphuric  Acid,  Chloride  of  Sulphur, 
Bromide  of  Sulphur,  Iodide  of  Sulphur,  Hydrothionic  Acid, 
Hydrothionous  Acid,  Salts  of  Ammonia  and  the  acids  contain- 
ing Sulphur,  .....  ,*°\  143 

SECTION  IV.  PHOSPHORUS — Oxide  of  Phosphorus,  Hypophospho- 
rous  Acid,  Phosphorous  Acid,  Phosphoric  acid,  Pyrophospho- 
ric  Acid,  Salts  of  Ammonia  and  the  acids  containing  Phos- 
phorus, Chlorides  of  Phosphorus,  Bromides  of  Phosphorus, 
Iodide  of  Phosphorus,  Hydruret  of  Phosphorus,  Bihydruret 
of  Phosphorus,  Sulphuret  of  Phosphorus,  .  .  v  156 

SECTION  V.  CARBON — Carbonic  Oxide,  Carbonic  Acid,  Salts  of 
Carbonic  Acid  and  Ammonia,  Chlorides  of  Carbon,  Chloro- 
carbonic  Acid,  Bromide  of  Carbon,  Iodide  of  Carbon,  Hydru- 
rets  of  Carbon,  Naptha  from  Coal  Tar,  and  Naphthaline, 
Coal  and  Oil  Gas,  Fire  Damp  &c.,  Chloride  of  Hydrocarbon, 
Bromide  of  Hydrocarbon,  Iodide  of  Hydrocarbon,  Cyanogen, 
Cyanous  Acid,  Cyanic  Acid,  Chlorides  of  Cyanogen,  Bro- 
mide of  Cyanogen,  Iodide  of  Cyanogen,  Hydrocyanic  Acid, 
Hydrocyanate  of  Ammonia,  Cyanide  of  Sulphur  Sulpho-cy 
anicAcid,  Bisulphuret  of  Carbon,  Xanthogen  and  Hydroxan- 
thic  Acid,  Phosphuret  of  Carbon,  .  .  .  164 

SECTION  VI.     BORON — Boracic  Acid,   Bichloride  of  Boron,  Fluo- 

boric  Acid,  Sulphuret  of  Boron,         *  ...     188 


CONTENTS.  XI 

Page. 

SECTION  VII.  SELENIUM— Oxide  of  Selenium,  Selenious  Acid, 
Selenic  Acid,  Chloride  of  Selenium,  Bromide  of  Selenium, 
Hydroselenic  Acid,  Sulphuret  of  Selenium,  Phosphuret  of  Se- 
lenium, .  ...  191 


CHAPTER  VIII. 


METALS. 

General  properties  of  the  metals,  .  .  195 

SECTION  I.  POTASSIUM — Oxides,  Chloride, ]  Bromide,  Iodide,  Hy- 
druret,  Nitruret,  Sulphuret,  Phosphuret,  and  Cyanide  of  Po- 
tassium, Alloys  and  Amalgams,  Salts  of  Potassa,  .  208 

SECTION  II.  SODIUM — Oxides,  Chloride,  Iodide,  &c.  Alloys  and 

Amalgams,  Salts  of  Soda,  Disinfecting  Liquid,  .  .  223 

SECTION  III.     LITHIUM — Oxide,  Chloride,  Salts  of  Lithia,  223 

SECTION  IV.     BARIUM — Oxides,  Chloride,  Bromide,   &c.   Salts  of 

Baryta,  .....  235 

SECTION  V.  STRONTIUM — Oxides,  Chloride,  Iodide,  &c.,  Salts  of 
Strontia,  .....  240 

SECTION  VI.     CALCIUM — Oxides,  Chloride,  &c.,  Chloride  of  Lime, 

Salts  of  Lime,  .....  243 

SECTION  VII.  MAGNESIUM — Oxide,  Chloride,  &c.,  Salts  of  Mag- 
nesia,   249 

SECTION  VIII.  ALUMINUM — Oxide,  Chloride,  &c.,  Salts  of  Alu- 
mina, .......  254 

SECTION  IX.     GLUCINUM— Oxide,  &c.,  .         .          .          .257 

SECTION    X.     YTTRIUM— Oxide  of  Yttrium,         .         .         .         .     258 
SECTION  XI.     ZIRCONIUM— Oxide,  &c.,          ....  259 

SECTION  XII.  SILICIUM — Oxide,  Chloride,  Bromide,  Fluoride,  &c,    260 
SECTION  XIII.  THORIUM— Oxide  of  Thorium,  ...         263 

SECTION  XIV.  MANGANESE — Oxides,  Acids,  Chloride,  &c.,  Salts 

of  Manganese,  .....  264 

SECTION  XV.  IRON — Oxides,     Chlorides,     Bromides,     Carburets, 

&c.,  Alloys,  Ferrocyanic  Acid,  Salts  of  Iron,  Ferrocyanates,  270 

SECTION  XVI.  ZINC — Oxide,  Chloride,  Iodide,  and  Sulphuret,  Al- 
loys, Salts  of  Zinc, 279 

SECTION  XVII.     TIN— Oxides,   Chlorides,  &c.,   Alloys,   Salts   of 

Tin, 284 

SECTION  XVIII.     CADMIUM— Oxide,  Chloride,  &c.,  Alloys,  Salts  of 

Cadmium, 288 

SECTION  XIX.     NICKEL— Oxides,  Alloys,  Salts  of  Nickel,          .      290 

SECTION  XX.     COBALT— Oxides,  Chloride,  &c.  Salts  of  Cobalt,      293 


xil  CONTENTS. 

Page. 

SECTION  XXI.  ARSENIC— Arsenious  and  Arsenic  Acids,  Chloride 
of  Arsenic,  Bromides,  Iodide,  Hydruret,  and  Sulphurets,  Al- 
loys of  Arsenic,  Arsenites,  Arseniates,  .  "  .  •  296 

SECTION  XXII.  MOLYBDENUM— Oxides  of  Molybdenum,  Molybdic 
Acid,  Chloride  of  Molybdenum,  Fluoride  and  Sulphuret, 
Molybdates,  303 

SECTION  XXIII.  CHROMIUM— Oxides  of  Chromium,  Chromic 
Acid,  Chlorochromic  Acid,  Fluochromic  Acid,  Sulphuret  and 
Phosphuret  of  Chromium,  Chromates,  .  •  •  305 

SECTION  XXIV.  VANADIUM — Oxides  of  Vanadium,  Vanadic  Acid, 

Chlorides  of  Vanadium,  Sulphurets,  &c,  .  .  309 

SECTION  XXV.  TUNGSTEN — Oxide  of  Tungsten,  Tungstic  Acid, 

Chlorides  of  Tungsten,  &c.,  .  .  •  .312 

SECTION  XXVI.  ANTIMONY — Oxide  of  Antimony,  Antimonious 
and  Antimonic  Acids,  Chlorides  of  Antimony,  Sulphurets,  Al- 
loys, Salts, 313 

SECTION  XXVII.  URANIUM — Oxide  and  Sulphuret  of  Uranium, 

Salts  of  Uranium,  .....  318 

SECTION  XXVIII.  COLUMBIUM — Oxide  of  Columbium,  Columbic 
Acid,  Chloride  of  Columbium,  Fluocolumbic  Acid,  Sulphuret 
of  Columbium, 320 

SECTION  XXIX.  CERIUM — Oxides  and  Sulphuret  of  Cerium,  Salts 

of  Cerium, 321 

SECTION  XXX.  TITANIUM— Oxide  of  Titanium,  Titanic  Acid,  Bi- 
chloride and  Bisulphuret  of  Titanium,  ...  322 

SECTION  XXXI.  TELLURIUM— Tellurous  Acid,  Telluric  Acid, 

Chlorides  of  Tellurium,  Telluretted  Hydrogen,  .  .  324 

SECTION  XXXII.  BISMUTH — Oxide,  Chloride,  Bromide,  Iodide, 

and  Sulphuret  of  Bismuth,  Alloys,  Salts,  .  .  326 

SECTION  XXXIII.  COPPER — Oxides,  Chlorides,  Sulphurets,  and 

Phosphuret,  Alloys,  Salts, 329 

SECTION  XXXIV,  LEAD — Oxides,  Chloride,  Iodide,  and  Sulphu- 
rets, Alloys,  Salts,  .....  335 

SECTION  XXXV.  MERCURY — Oxides,  Chlorides,  Bromides,  Io- 
dides, Sulphurets,  and  Bicyanide  of  Mercury,  Amalgams, 
Salts  of  Mercury,  .....  340 

SECTION  XXXVI.  SiLvln— Oxides,  Chloride,  Bromide,  Iodide, 

Sulphuret,  and  Cyanide  of  Silver,  Alloys,  Salts  of  Silver,  348 

SECTION  XXXVII.  GOLD— Oxides,  Chlorides,  Bromide,  Iodide, 

Sulphuret  and  Phosphuret  of  Gold,  Alloys,  .  353 

SECTION  XXXVIII.  PLATINUM — Oxides,  Chlorides,  and  Sulphu- 
ret, Sulphate  of  Platinum,  Alloys,  .  .  .356 

SECTION  XXXIX.     PALLADIUM— Oxides  of  Palladium,  .          359 


CONTENTS.  Xlii 

Page. 

SECTION  XL.    RHODIUM— Oxides  of  Rhodium,  .        359 

SECTION  XLI.     OSMIUM— Oxides,  &c.  •  360 

SECTION  XLII.    IRIDIUM— Oxides,  &c.  .  •  .         360 

CHAPTER  IX. 

VEGETABLE    SUBSTANCES. 

Preliminary  Remarks,  .  .  .  362 

SECTION  I.  VEGETABLE  ACIDS — Acetic  Acid,  Pyroligneous  Acid, 
Kreosote,  Acetates,  Oxalic  Acid  and  the  Oxalates,  Oxamide, 
Tartaric  Acid  and  the  Tartrates,  Racemic  or  Paratartaric 
Acids,  Citric  Acid  and  the  Citrates,  Malic  Acid  and  the  Mal- 
ates,  Benzoic  Acid  and  the  Benzoates,  Benzule,  Gallic  and 
Pyrogallic  Acids  and  the  Gallates,  Ellagic  Acid,  Aspartic, 
Boletic,  Camphoric,  Carbazotic,  Chloroxalic,  Caincic,  Crame- 
ric,  Croconic,  Igasuric,  Indigotic,  Kinic,  Laccic,  Lactucic, 
Meconic,  Mellitic,  Moric  or  Moroxylic,  Mucic  or  Saccholic- 
tic,  Pectic,  Phosphoric  and  Hydrocyanic,  Suberic,  Succinic, 
Ulmic,  Valerianic,  and  Zumic  Acids,  .  .  .  363 

SECTION  II.  VEGETABLE  ALKALIES — Morphine  and  its  Salts,  Nar- 
cotine,  Cinchonine,  Quinine,  Strychnine,  Brucine,  Emetine, 
Veratrine,  Sanguinarine,  Atropine,  Buxine,  Corydaline,  Cro- 
tonine,  Curarine,  Cynapine,  Daphnine,  Daturine,  Delphine, 
Digitaline,  Essenbeckine,  Eupatorine,  Hyoscyamine,  Nico- 
tine, Solanine,  Violine,  ....  377 

Substances  somewhat  allied  to  the  preceding,  but  not  alkaline — 
Amydalin,  Asparagin,  Bassorin,  Caffein,  Cathartin,  Chloro- 
phyle,  Colocyntin,  Columbin,  Conein,  Cytisin,  Dahlin,  Dra- 
cin,  Fungin,  Gentianin,  Hematin,  Imperatorin,  Inulin,  Legu- 
min,  Liriodendrin,  Lupulin,  Madarin,  Medulin,  Olivile,  Paraf- 
fin and  Eupion,  Picrotoxin,  Piperin,  Plumbagin,  Polychroite, 
Populin,  Rhubarbarin,  Salicin,  Sarcocoll,  Scillitin,  Suberin, 
Tiglin,  Ulmin,  Zanthopicrite,  Bitter  Principle,  Extractive 
Matter,  .......  384 

SECTION  III.  SUBSTANCES  WHICH  IN  RELATION  TO  OXYGEN  CONTAIN 
AN  EXCESS  OF  HYDROGEN — Oils,  Fixed  Oils,  Volatile  or  Essen- 
tial Oils,  Camphor,  Coumarin,  Resins,  Amber,  Balsams,  Gum, 
Resins,  Caoutchouc,  Wax,  Alcohol,  Alcohol  in  Wine,  &c., 
Ether,Ethers  of  the  first  Class,  Sulphuric  Ether,  Sulphovinic 
Acid,  Phosphoric  Ether,  Ethers  of  the  second  class,  Muriatic, 
Chloric,  Hydriodic,  Fluoric  and  Fluoboric  Ethers,  Ethers  of 
the  third  class,  Nitric  and  Acetic  Ether,  Bituminous  substan- 
ces, Bitumen,  Naptha,  Petroleum,  Asphaltum,  Mineral  Pitch 
or  Maltha,  Retinasphaltum,  Pit-Coal,  Glance  Coal  or  An- 
thracite,   .380 


XIV  CONTENTS. 

Page. 
SECTION  IV.     SUBSTANCES,  THE  OXYGEN  AND  HYDROGEN  OF  WHICH 

ARE  IN  EXACT  PROPORTION  FOR  FORMING  WATER — Sugar,  Man- 
na, Sugar  of  Grapes,  of  the  Maple,  of  Beets,  £c.,  Honey, 
Molasses,  Starch  or  Fecula,  Arnidine,  Hordein,  Gum,  Mucil- 
age, Lignin  or  Woody  Fibre,  ....  399 
SECTION  V.  SUBSTANCES  WHICH  DO  NOT  BELONG  TO  EITHER  OF  THE 
PRECEDING  SECTIONS — Colouring  Matter  and  Dyes,  Tannin, 
natural  and  artificial,  Gluten,  Yeast,  Vegetable  Albumen, 
Fermentation.  Panary,  Saccharine,  Vinous,  Acetous,  and  Pu- 
trefactive Fermentations,  .  .  .  420 

CHAPTER  X. 

ANIMAL    SUBSTANCES. 

Preliminary  Remarks.  .....  408 

SECTION  I.  ANIMAL  ACIDS — Uric,  Pyro-Uric,  Purpuric,  Erythric, 
Rosacic,  Amniotic,  Lactic,  Formic,  Caseic,  Sebacic.  Choles- 
teric,  Stearic,  Margaric,  Oleic,  Phocenic,  Butyric,  Caproic, 
Capric,  Hircic,  and  Cetic  Acids,  .  .  408 

SECTION  II.  OLEAGINOUS  SUBSTANCES. — Train  Oil,  Spermaceti  Oil, 
Dippel's  Oil,  Hogslard,  Suet,  Butyrine,  Phocenine,  Hircine, 
Adipocire,  Cholesterine  and  Ambergris,  .  .  .  411 

SECTION  III.  SUBSTANCES  WHICH  ARE  NEITHER  ACID  NOR  OLEAGIN- 
OUS— Fibrin  or  Animal  Gluten,  Albumen,  Gelatin,  Urea,  Su- 
gar of  Milk,  Sugar  of  Diabetes,  .  .  .  413 

SECTION  IV.  THE  MORE  COMPLEX  ANIMAL  PRODUCTS — The  Blood 
and  its  constituents,  Respiration,  Animal  Heat,  Saliva,  Pan- 
creatic Juice,  Gastric  Juice,  Bile,  Biliary  Calculi,  Chyle, 
Milk,  Eggs,  Humours  of  the  Eye,  Tears,  Mucus,  Pus,  Sweat, 
Urine  and  Urinary  Concretions,  Solid  parts  of  Animals,  Bones, 
Teeth,  Shells  of  Eggs,  Lobsters,  &c.,  Horn,  Tendons,  Hair, 
Wool  and  Feathers,  Muscle.  414 

APPENDIX. 

TABLE  of  Atomic  Weights  and  Symbols.      .  .  .  425 

TABLE  showing  the  Proportions  in  which  several  Gaseous  Bodies 

combine  by  Volume,  .....        428 


f  UNIVERf  ITY 

\      r*         OF 

jUFQR^bX  ;  '-   ; 

MANUAL  OF  CHEMISTRY. 


DEFINITION    OP    CHEMISTRY. 

CHEMISTRY*  has  been  variously  defined.  By  Dr.  Black  it  was  de- 
nominated "  the  science  of  heat  and  mixture.'*  Modern  chemists, 
however,  have  given  it  a  wider  range.  Thomson  calls  it  the  sci- 
ence which  treats  of  those  events  and  changes  in  natural  bodies, 
which  are  not  accompanied  by  sensible  motions. — Syst.  of  Chem.  i. 
18.  Brande  considers  it  "the  object  of  chemistry  to  investigate  all 
changes  in  the  constitution  of  matter,  whether  effected  by  heat,  mix- 
ture or  other  means." — Man.  of  Ckem.  1.  According  to  Berzelius, 
"  chemistry  is  the  science  which  makes  us  acquainted  with  the  com- 
position of  bodies  and  with  the  manner  in  which  they  act  upon  each 
other."— Trait,  de  Chim.  i.  31. 

Chemistry  borders  closely  in  many  instances  upon  Natural  Philoso- 
phy ;  but  the  distinction  can  be  easily  drawn. 

It  is  the  office  of  natural  philosophy  to  investigate  the  sensible  mo- 
tions of  all  bodies  ;  whereas  chemistry  studies  the  constitution  and 
qualities  of  these  bodies. 

The  natural  philosopher  contemplates  whole  masses  and  ascertains 
their  properties  ;  while  the  chemist  notices  the  operations  of  their  par- 
ticles, observes  their  reciprocal  actions  and  seeks  to  discover  all  the 
changes  that  may  occur. 

Thus  in  examining  our  atmosphere,  when  studied  as  a  whole,  its 
weight,  pressure,  density  and  elasticity,  are  subjects  falling  within 
the  province  of  natural  philosophy';  but  when  we  endeavor  to  dis- 
cover the  elements  of  which  this  air  is  composed,  the  changes  which 
it  undergoes,  by  heat  or  combination,  and  the  phenomena  which  at- 
tend these  changes,  we  are  within  the  boundaries  of  chemistry. 

The  business  of  the  chemist,  therefore,  is  to  interrogate  nature, 
and  thus  to  make  himself  acquainted  with  the  ultimate  constitution 
of  bodies.  When  this  is  effected,  he  is  furnished  with  the  means  of 
imitating  her  in  some  of  her  most  interesting  operations,  and  thus  in 
many  instances,  of  contributing  largely  to  individual  as  well  as  to  na- 
tional wealth  and  prosperity. 

Chemistry  is  divided  into — 

I.  The  general  forces,  or  powers  productive  of  chemical  phenome- 
na and  the  laws  which  govern  them :  or  the  general  theory  of  the 
science. 

II.  The  particular  effects  which  are  produced  in  different  bodies  by 
the  agency  of  these  general  powers  ;   or  the  chemical  history  of  in- 
dividual substances. 

*The  term  chemistry  is  probably  derived  from  the  Greek  word  Chemia, 
originally  applied  to  the  art  of  making  gold  and  silver.  The  Arabians  by 
prefixing  the  article  gave' it  the  name  of  Alchemy. — Thomson's  History 
of  Chemistry. 

B 


1 4  ATTRACTION — COHESION. 

The  general  powers,  or  as  they  are  sometimes  called,  general  pro- 
perties of  matter,  or  imponderable  substances,  are 

-    ATTRACTION. 
HEAT. 
LIGHT. 
ELECTRICITY. 
MAGNETISM. 


CHAPTER  I. 


ATTRACTION. 

The  term  attraction  is  employed  to  express  that  unknown  principla 
which  causes  distant  bodies  to  approach  each  other,  and  to  resist  a 
separation  with  some  degree  of  force. 

Attraction  may  be, 

I.  Remote  ;  when  it  acts  on  masses  of  matter  at  sensible  distances  ; 
as  in  gravitation,  electricity,  and  magnetism. 

II.  Contiguous ;  when  it  acts  on  masses  of  matter  at  insensible  dis- 
tances ;  as  in  cohesion  and  in  chemical  affinity. 

Contiguous  attraction  is  of  two  kinds,  viz  :  homogeneous  and  hetero- 
geneous, or  cohesion  and  affinity.  The  former  takes  place  between 
bodies  of  the  same  nature,  and  the  latter  between  those  which  are 
different. 

SECTION  I. 

COHESION. 

SYNONYMES.  Attraction  of  Aggregation — Cohesive  Affinity — Corpus- 
cular,  or  Molecular  Attraction — Homogeneous  Affinity. 

Cohesion  may  be  denned  to  be  that  force  or  power  by  which  parti- 
cles or  atoms  of  the  same  kind  are  brought  into  contact  and  retained 
in  that  situation. 

Cohesion  is  exerted  in  different  bodies  with  different  degrees  of 
force.  In  solids,  its  force  is  exerted  with  the  greatest  intensity;  in 
liquids,  it  acts  with  much  less  energy;  and  in  aeriform  bodies  it  is  doubt- 
ful whether  it  exists  at  all.  Thus  water  in  a  solid  state  has  considera- 
ble cohesion,  which  is  much  diminished  when  it  becomes  liquid,  and 
is  entirely  destroyed  as  soon  as  it  is  changed  into  vapour. 

The  force  of  cohesion  in  solid  bodies  which  is  denominated  tenacity, 
is  measured  by  the  weight  necessary  to  break  them,  or  rather  to  pulj 
them  asunder.  Heat  is  excited  at  the  same  time,  a  good  illustration 
of  which  occurs  in  the  process  of  wire  drawing.  [An  abstract  of  Mr. 
Rennie's  elaborate  experiments  on  the  cohesive  force  of  various  solids 
will  be  found  in  Ure's  Chem.  Dictionary.  ] 

In  liquids  the  force  of  cohesion  is  demonstrated  by  the  spherical 
figure  which  they  assume  when  suffered  to  form  drops,  The  drop  is 


COHESION.  15 

spherical,  because  each  particle -of  the  fluid  exerts  an  equal  force  in 
every  direction,  drawing  other  particles  towards  it  on  every  side,  as 
far  as  its  power  extends.  To  the  same  cause  is  owing  the  property 
possessed  by  all  liquids  of  remaining  heaped  up  above  the  brims  of 
the  vessels  which  contain  them. 

Other  examples  of  cohesion. 

1.  Similar  portions  being  cut  off  with  a  clean  knife  from  two  lead- 
en bullets  and  the   fresh  surfaces  being  brought  into  contact  with  a 
slight  turning  pressure,  the  bullets  cohere,  almost  as  if  they  had  been 
originally  cast  together. 

2.  Fresh  cut  surfaces  of  India  rubber  adhere  in  a  similar  manner. 

3.  Two  pieces  of  perfectly  smooth  glass  or  marble  laid  upon  each 
other  adhere  with  great  force. 

It  has  been  supposed  that  in  some  of  the  above  cases  the  attractive 
force  is  confined  to  the  surfaces  of  the  masses,  and  it  has  been  called 
adhesion.  Mr.  Ruhland  has  given  a  table  exhibiting  the  weights 
which  were  found  necessary  to  separate  equal  surfaces  of  different 
bodies  from  the  same  liquids.  [Gorhams  Chem.  i.  6.  Ann.  of  Phil. 
vii.  20.]  Dr.  Thomson  considers  adhesion  as  exhibiting  the  charac- 
teristic marks  of  chemical  affinity  and  as  affording  a  particular  case  of 
the  action  of  that  power. 

Cohesion  is  weakened  by  the  following  causes  : 

I.  By  Heat.  When  a  fusible  body  is  exposed  to  the  influence  of  heat, 
its  volume  is  at  first  augmented,  and  this  increase  of  bulk  is  in  conse- 
quence of  the  separation  to  a  certain  degree  of  its  constituents.     Co- 
hesion is  thus  lessened,  though  not  destroyed,  and  hence  if  heated 
zinc  be  struck  with  a  hammer,  much  less  force  will  be  required  to  dis- 
integrate it,  than  if  it  were  at  the  ordinary  temperature  of  the  air.     If 
the  heat  be  continued,  the   particles  of  the  metal  will  be  so  far  re- 
moved from  each  other,  as  to  allow  of  free  motion,  and  it  will  become 
liquid.     By  raising  the  heat  still  higher,  while  the  metal  is  not  in  con- 
tact with  the  air,  all  cohesion  will  be  removed  and  it  will  be  resolved 
into  vapour  or  an  elastic  fluid. 

II.  By  Mechanical  violence.     Under  this  head  may  be  arranged  seve- 
ral processes  which  are  highly  useful  in  the  laboratory,  as — 

Pulverization  and  trituration ;  by  which  substances  are  reduced  to 
powder,  generally  performed  by  means  of  pestles  and  mortars. 

Levigation  ;  a  process  similar  to  trituration,  except  that  the  rubbing 
is  assisted  by  the  addition  of  a  liquid  in  which  the  solid  matter  under 
operation  is  not  soluble. 

Granulation;  effected  either  by  pouring  the  substance  while  in 
fusion  into  cold  water,  or  by  agitating  it  in  a  box. 

Sifting ;  employed  for  the  purpose  of  obtaining  bodies  in  powder 
of  an  equal  degree  of  fineness  throughout,  performed  by  instruments 
termed  sieves. 

III.  By  the  influence  of  a  more  powerful  attraction.     Thus  if  a  mass  of 
lime  be  immersed  in  vinegar,  it  gradually  lessens  and  finally  disappear!. 
Here  an  attractive  force  has  been  introduced  which  is  superior  to  the 
attraction  of  the  particles  of  lime  for  each  other,  and  consequently 
they  are  separated. 


16  CRYSTALLIZATION. 

The  effects  of  the  exertion  of  cohesion  are, 

1.  To  unite  the  particles  of  bodies  in  a  confused  manner,  without 
any  regularity  of  form. 

2.  To  bring  them  together  in  a  determinate  mode  so  as  to  form 
regular  geometrical  figures  or  crystals.     The  latter  is  the  most  fre- 
quent. 

CRYSTALLIZATION. 

When  we  diminish  in  any  manner  the  cohesion  of  a  solid  body  so 
as  to  render  it  liquid  or  gaseous  and  afterwards  remove  the  cause  of 
this  change,  the  body  returns  to  its  former  state  and  the  molecules  ar- 
range themselves  in  a  determinate  manner,  or  in  the  form  of  crystals. 
Hence  when  a  body  passes  from  a  gaseous  or  liquid  state  to  that  of  a 
solid,  it  crystallizes;  but  if  this  passage  be  too  rapid,  the  crystallization 
will  be  confused. 

The  most  common  agents  employed  to  crystallize  bodies  are  water 
and  heat ;  alcohol  is  also  sometimes  made  use  of  in  certain  analyses. 

I.    Water.     This  agent  is  employed  in  two  ways,  viz. 

a.  To  dissolve  the  body  by  the  aid  of  heat  and  then  to  allow  the 
solution   to  cool.     In  this  case  it  will  generally  be  only  necessary  to 
continue  the  process  of  evaporation  until  a  drop  of  the  solution  when 
placed  upon  a  cold  body  shows  a  tendency  to  crystallize  ;   or  at  least 
until  a  film  or  pellicle  appears  on  its  surface.     This  proves  that  the  at- 
traction of  the  saline  particles  for  each  other  is  becoming  superior  to 
their  attraction  for  the  water.     In  this  case,  crystallization  takes  plaee 
because  hot  water  generally  dissolves  a  greater  quantity  of  a  salt  than 
cold  water,  and  when  it  has  become  saturated  a  portion  is  necessarily 
deposited  as  the  water  cools.     There  are,  however  a  few  exceptions  to 
the  law  that  salts  are  more  soluble  in  hot  than  in  cold  water,  and  Mr. 
Graham  suggests  that  the  efflorescent  salts  generally  belong  to  this 
class. — Phil.  Mag.  and  Ann.  i.  7. 

b.  To  leave   the  cold  solution  to  spontaneous  evaporation.     In  this 
case  the  water  by  evaporation  is  brought  to  the  point  at  which  it  is 
unable  to  hold  the  salt  in  solution. 

In  both  of  the  above  cases,  crystals  generally  retain  a  portion  of 
water,  which  is  termed  the  water  of  crystallization,  and  the  salts  con- 
taining it  are  denominated  hydrous  salts.  These  salts  when  heated 
liquify  and  undergo  a  process  which  is  called  watery  fusion.  Alum 
offers  a  familiar  example. 

In  a  few  casea  however,  salts  do  not  retain  any  water  of  crystalliza- 
tion and  they  are  then  termed  anhydrous  salts. 

Salts,  in  crystallizing,  frequently  enclose  mechanically  within  their 
texture  particles  of  water,  by  the  expansion  of  which,  when  heated, 
the  salt  is  burst  with  a  crackling  noise  into  smaller  fragments.  This 
phenomena  is  known  by  the  name  of  decrepitation ;  and  it  is  observed 
to  be  most  powerful  in  those  crystals  which  contain  no  water  of  cry  s- 
tallization  ;  as  the  nitrates  of  baryta  and  of  lead. 

Some  salts  part  with  their  water  of  crystallization  by  a  simple  ex- 
posure to  a  dry  air,  when  they  are  said  to  effloresce ;  but  there  are  other 
salts  which  deliquesce  or  attract  water  from  the  atmosphere.  Car- 
bonate of  potash  is  a  deliquescent  salt  ;  carbonate  of  soda  an  efflores- 
cent one.  [For  a  table  of  the  action  of  the  atmospheric  air,  on  some 
of  the  most  common  salts,  see  Parke's  Chem.  Catechism,  231,  8th  ed.] 


CRYSTALLIZATION.  17 

II.  Heat.    There  are  two  methods  of  employing  this  agent,  viz. 

a.  To  expose  the  body  to  heat  until  it  has  melted,  then  to  let  it  cool 
slowly  and  without  agitation,  till  a  crust  has  formed  on  its  surface,  to 
pierce  this  crust  and  decant  the  liquid  contained  in  the  interior.     We 
then  obtain  the  outer  portion  in  the  form  of  a  solid  crystalline  bed, 
sometimes  resembling  a  geode.     This  effect  can  be  finely  exhibited  by 
treating  in  such  a  manner  sulphur,  or  lead,  bismuth  and  some  other  of 
the  semi-crystalline  rnetals. 

b.  To  reduce  the  body  to  a  state  of  vapour  and  to  condense  it  gradu- 
ally.    This  however,  is  not  always  practicable,  because  few  of  the 
solids  can  be  volatilized.     The  process  is  generally  called  Sublimation. 

Exp.  Put  powder  of  corrosive  sublimate  or  arsenic  in  a  dry  flask, 
obstruct  the  mouth  slightly  and  apply  heat.  The  vapour  rises  and 
forms  crystals  in  the  upper  part.  More  heat  is  required  in  the  case  of 
arsenic  than  in  that  of  corrosive  sublimate. 

III.  Alcohol.     This  is  generally  employed  by  applying  heat  a«d  then 
allowing  the  solution  to  cool   as  above.     The  great   utility  of  this 
agent  depends  upon  the  fact,   that  a  few  salts  only  are  soluble  in  it. 
Hence  it  is  often  made  use  of  to  separate  such  sails  from  others  with 
which  they  may  be  combined,     It  is  scarcely  necessary  to  observe 
that  in  such  cases  the  purest  alcohol  must  be  employed.     [For  a  table 
of  substances  soluble  in  alcohol,  see  Henry's  Chcm.  llth  ed.  ii.  653.] 

Several  circumstances  affecting  the  process  of  crystallization  de- 
serve to  be  noticed.  Among  these  are, 

1.  Rapidity  of  evaporation.     When  the  heat  is  high  and  the  evapo- 
ration very  rapid,  the  crystallization  is  confused. 

2.  The  access  of  atmospheric  air.     This  under  certain  circumstances 
produces  instant    crystallization   in   some  saline   solutions.      Those 
which  are  the  most  remarkable  on  this   account  are   carbonate  and 
sulphate  of  soda.     Hot  saturated  solutions  of  these  salts  in  well  cork- 
ed phials  may  be  cooled  down  without  the  deposition  of  any   crystals, 
but  as  soon  as  the  corks  are  withdrawn,  crystals  begin  to  form  and  at 
the  same  time  the  temperature  rises.     Dr.  Thomson  has  satisfactorily 
proved  that  the  water  of  crystallization  of  the  salt  which  crystallizes, 
gives  out  its  latent  heat,  and  that  this  evolution  is  the  cause  of  the  in- 
crease of  temperature  observed.* — Ann.  of  Phil.  xix.  169. 

*  The  theory  of  this  singular  phenomenon  hat  riot  yet  been  well  settled. — 
That  it  does  not  depend  on  atmospheric  pressure  is  proved  by  the  fact  that 
the  solution  may  be  cooled  in  open  vessels  without  becoming  solid,  provided 
its  surface  be  covered  wi'h  a  film  of  oil,  as  first  shown  by  Gay  Lussac  ;  and,  as 
Dr.  Turner  states,  that  the  experiment  also  succeed?  without  the  use  of  oil  by 
causing  the  air  of  the  flask  to  communicate  with  the  atmosphere  by  means  of  a 
moderately  narrow  tube. 

Mr.  Graham  supposes  the  effect  of  air  to  arise  from  a  certain  chemical  ac- 
tion upon  water.  He  has  shown  that  gases  which  are  more  freely  absorbed 
than  atmospheric  air,  act  more  rapidly  in  producing  crystallization.  And  it 
would  seem  from  his  experiments  that  the  rapidity  of  crystallization,  occa- 
sioned by  the  contact  of  gaseous  matter,  is  proportional  to  the  degree  of  its 
affinity  for  water  Upon  this  principle  also,  he  accounts  for  the  fact  that  so- 
lutions of  sulphate  of  soda  which  have  not  been  boiled  are  less  affected  by 
exposure  to  the  air  than  well  boiled  solutions;  for  the  former  still  retain 
most  of  their  air,  and  do  not  absorb  air  so  eagerly  on  exposure  as  solutions 
which  have  been  boiled. — Phil.  Mag.  and  Annals,  iv.  215. 

On  the  other  hand,  Dr.  H.  O^den  contends  that  the  access  of  air  is  not  neces- 


18  CRYSTALLIZATION. 

3.  The,  nature   of  the,  liquor  in  which  the  crystals  are,  formed.     Dr. 
Woolner  has  ascertained  that  this  often  influences  the  fundamental  or 
primitive  forms  of  crystals.     Thus  he  says  that  when  a  small  portion 
of  solution  ©f  sulphate  of  iron  is  poured  into  a  solution  of  alurn  and 
the  whole  allowed  to  crystallize,  the  sulphate  of  iron  assumes  the  octa- 
hedral form  of  the  alum,  although  these  octahedral  crystals  contain 
scarcely  a  trace  of  alum. — Edin.  Neio  Phil.  Jour.  i.  189. 

4.  \The   immersion    of  some  foreign  body   into  the  saline  solution. 
This  serves  as  a  nucleus  or  attracting  point  around  which  the  parti- 
cles as  they  are  deposited  may  be  attached.     Hence  many  of  the  salts 
are  found  concreted  around  sticks  or  twigs,  and  the  crystals  of  sugar 
are  arranged  around  threads.     A  crystal  of  the  same  kind  as  that  held 
in  solution  also  answers  the  purpose. 

5.  Light.     Of  this,  instances  are  observed  in  the  bottles  of  camphor 
placed  in  druggists'  windows,  where  the  crystals  are  always  most  co- 
pious on  the  side  exposed  to  the  light.     Chaptal  found  that  by  using 
a  solution  of  a  metallic  salt,  and  shading  the  greater  part  of  the  vessel 
with  black  silk,  capillary  crystals  shoot  up  the  uncovered  sides,  and 
that  the  extent  of  the  exposed  partis  distinctly  marked  by  the  limit  of 
crystallization.     The  phenomenon   termed  saline  vegetation,   consist- 
ing in  the  creeping  of  the  salt  around  the  edge  of  the  vessel,  is  also  re- 
ferred by  Chaptal  to  the  influence  of  light.     For  the  perfect  success  of 
this  experiment,  the  edges  of  the  vessel  should  be  smeared  with  oil. 

6.  Electricity.     It  has  been  repeatedly  remarked  that  saline  solu- 
tions which  have  not  yielded  crystals,  after  having  been  sufficiently 
concentrated  and  left  undisturbed  for  several  days,  have  suddenly  de- 
posited  an   abundant  crop,  during,  or  immediately  after  a  thunder 
storm.     Dr.  lire  has  shown  that  negative  electricity  facilitates,  and 
positive  electricity  retards  the  formation  of  crystals. — Erandes  Jour. 
iv.  106. 

Crystallographers  have  observed  that  certain  crystalline  forms  are 
peculiar  to  certain  substances.  Thus,  calcareous  spar  crystallizes  in 
rhombs  ;  fluor  spar  in  cubes,  and  quartz  in  six  sided  pyramids  ;  and 
these  forms  are  so  far  peculiar  to  those  substances,  that  fluor  spar  is 
never  found  in  rhombs  or  six-sided  pyramids,  nor  does  calcareous* 
spar  or  quartz  ever  occur  in  cubes.  Crystalline  form  may,  therefore, 
serve  as  a  ground  of  distinction  between  different  substances.  It  is 
accordingly  employed  by  mineralogists  for  distinguishing  one  mine- 
ral species  from  another  }  and  it  is  very  serviceable  to  the  chemist  as 
affording  a  physical  character  for  salts.  A  notice  of  this  subject  there- 
fore should  form  part  of  every  treatise  on  chemistry. 

The  surfaces  which  limit  the  figure  on  crystals  are  called  the  planes 
or  Jaces,  and  are  generally  flat.  The  lines  formed  by  the  junction 
of  two  planes,  are  called  edges,  and  the  angle  formed  by  two  such 
edges  is  a  plane  angle.  A  solid  angle  is  the  point  formed  by  the  meet- 

sary  lo  the  process*  of  crystallization.  Me  asserts  that  it  often  occurs  when  the 
vessel  is  closed,  by  mere  agitation,  without  opening  it,  (a  fact  which  I  have 
also  observed,  and  to  this  he  also  ascribes  the  results  of  Mr.  Graham.)  He 
also  shows  that  tins  pecu'iar  property  of  resisting  crystallization  is  not  con- 
fined to  any  gonns  of  salts  in  particular,  but  enumerates  several  alkaline, 
earthy  and  metallic  sails  which  will  exhibit  this  property.  Among1  which  are 
the  sulphate,  carbonate,  acetate,  and  phosphate  of  soda,  the  tartrate  of  potash 
and  soda,  ferrocyanate  of  potnsh,  sulphate  ef  magnesia,  the  muriates  of  lime 
and  barytes  and  the  sulphate  of  copper. — New  Edin.  Jour.  xiii.  309. 


CRYSTALLIZATION. 


19 


ing  of  at  least  three  planes.  The  planes  which  terminate  a  prism 
are  called  terminal  planes  ;  those  at  the  sides  lateral  planes ;  the  face 
on  which  a  crystal  is  supposed  to  stand  is  called  a  base.  When  the 
end  of  a  crystal  is  formed  by  two  planes  inclined  to  each  other  like 
the  roof  of  a  house,  it  is  said  to  be  culminated ;  if  three  or  more 
planes  meeting  in  a  solid  angle,  terminate  the  prism,  they  form  a 
pyramid  which  is  called  the  summit ;  the  planes  which  form  the  sum- 
mit are  called  acuminating  planes,  and  the  edges  produced  by  their 
junction,  edges  of  the  pyramid.  When  an  edge  or  solid  angle  is  cut 
off  and  replaced  by  a  single  new  face,  it  is  said  to  be  truncated ;  if  by 
two  or  more  new  faces,  it  is  bevelled.  A  very  short  prism  is  called  a 
table. 

The  forms  of  crystals  are  very  various.  They  are  divided  by  crys- 
tallographers  into  what  are  called  primitive,  primary,  derivative,  or  fun- 
damental forms,  and  into  secondary  or  dsrived  forms. 

The  number  of  primary  forms  is  differently  stated  by  different  au- 
thors, according  to  the  system  which  they  adopt.  The  most  simple, 
however,  is  that  which  reduces  these  forms  to  the  following,  viz. 


1.  The  cube. 


2.  The  tetrahedron. 


3.  The  Octahedron. 


4.  The  six-sided  prism. 


5.  The  rhombic  dodecahedron. 


6.  The  dodecahedron  with  isosceles  triangular 
faces. 


20  CRYSTALLIZATION. 


7.  The  rhomb. 


These  primitive  forms  by  farther  mechanical  analysis  may  be  redu- 
ced to  three  integral  elements. 

1.  The  parallelepiped,  or  simplest  solid  having  six  surfaces,  paral- 
lel, two  and  two. 


2.  The  triangular  or  simplest  prism,  bounded 
by  five  surfaces. 


3.  The  tetrahedron  or  simplest  pyramid,    bounded  by  four  surfaces. 

The  secondary  forms  are  supposed  to  arise  from  decrements  of  par- 
ticles taking  place  on  different  edges  and  angles  of  its  primitive  forms. 
Thus  a  cube,  having  a  series  of  decreasing  layers  of  cubic  particles 
upon  each  of  its  six  faces,  will  become  a  dodecahedron,  if  the  decre- 
ment be  upon  the  edges  ;  but  an  octahedron,  if  upon  the  angles  ;  and 
by  irregular,  intermediate,  and  mixed  decrements,  an  infinite  variety 
of  secondary  forms  would  ensue. 

There  are  some  appearances  in  crystallography  to  which  the  above 
explanation  will  not  apply.  A  slice  of  fluor  spar,  for  instance,  ob- 
tained by  making  two  successive  and  parallel  sections,  may  be  divid- 
ed into  acute  rhomboids  ;  but  these  are  not  the  primitive  forms  of 
the  spar,  because  by  the  removal  of  a  tetrahedron  from  each  extrem- 
ity of  the  rhomboid,  an  octahedron  is  obtained.  Thus  as  the  whole 
mass  of  fluor  may  be  divided  into  tetrahedrons  and  octahedrons,  it  be- 
comes a  question  which  of  these  forms  is  to  be  called  primitive,  es- 
pecially as  neither  of  them  can  fill  space  without  leaving  vacuities, 
a  structure  not  adapted  to  form  the  basis  of  a  permanent  crystal.  To 
obviate  this  difficulty,  Dr.  Wollaston  suggested  that  the  integrant  par- 
ticles of  all  crystals  might  be  considered  as  spheres  or  spheroids, 
which  by  their  mutual  attraction  have  assumed  that  arrangement 
which  bringsjthem  as  near  as  possible  to  each  other ;  and  this  view 
of  the  subject  has  been  confirmed  by  the  experiments  of  Mr.  Daniell. 
[Wollaston  in  Phil.  Trans.  1813.  Daniell  in  Brandt's  Jour.  i.  24.] 
But  although  the  preponderance  of  evidence  is  rather  on  the  side  of 
the  spherical  form  of  atoms,  this  opinion  is  attended  with  difficulties 
which  in  the  present  state  of  our  knowledge  cannot  be  obviated. 
Such  are  some  of  the  facts  developed  by  Isomorphism. — See  Thom- 
son1 s  Inorganic  Chcm.  i.  16. 

The  primitive  forms  of  crystals  can  be  ascertained — 1  st,  by  me- 
chanical division  or  cleavage  ;  and  2d,  by  the  action  of  fluid  men- 
strua. For  our  knowledge  of  the  latter  we  are  wholly  indebted  to  Mr. 
Daniell  ;  and  the  fact  is  well  shown  by  plunging  into  a  tumbler  full  of 
cold  water,  a  shapeless  mass  of  alum,  the  surface  of  which  becomes  in 
a  few  days,  eaten  and  carved  out  into  a  variety  of  regular  cryst- 
alline forms. 

The  process  called  cleavage  consists  in  separating  thin  layers  or 
slices  from  the  sides,  edges  or  angles  of  a  crystallized  substance  in  a 


CRYSTALLIZATION.  21 

given  direction.  Many  crystallized  substances  are  very  obviously 
composed  of  thin  plates  or  laminae,  which  by  a  careful  operation  may 
be  separated  from  each  other,  without  presenting  the  appearance  of 
a  fracture.  The  planes  in  which  these  laminae  are  applied  to  each 
other,  are  called  the  natural  joints  of  a  crystal.  The  direction  in 
which  it  may  be  cleaved  is  called  the  direction  of  cleavage.  Some 
times  a  crystal  is  cleavable  only  in  one  direction,  and  is  then  said  to 
have  a  single  cleavage.  Others  may  be  cleaved  in  two,  three,  four  or 
more  directions,  and  are  said  to  have  a  double,  treble,  fourfold  cleavage, 
and  so  on  according  to  their  number. 

8.  It  was  at  one  time  supposed  that  substances  of  different  composition 
never  assumed  precisely  the  same  primitive  form.  But  the  researches 
of  Professor  Mitscherlich  have  proved,  that  certain  substances  are 
capable  of  being  substituted  for  each  other  in  combination  without 
influencing  the  crystalline  form  of  the  compound.  This  discovery  has 
led  to  the  formation  of  groups,  each  comprehending  substances  which 
crystallize  in  the  same  manner,  and  which  are  hence  said  to  be  isomor- 
phous.  One  of  the  most  instructive  of  these  groups  includes  the  salts 
of  arsenic  and  of  the  phosphoric  acid.  Thus  the  neutral  phosphate  and 
biphosphate  of  ammonia  correspond  to  the  arseniate  and  biarseniate  of 
ammonia  ;  and  the  biphosphate  and  biarseniate  of  potash  have  the 
same  form.  Indeed  each  arseniate  has  a  corresponding  phosphate,  hav- 
ing the  same  form,  the  same  number  of  equivalents  of  acid,  alkali  and 
water  of  crystallization,  and  differing  in  fact  in  nothing  except  that 
one  series  contains  arsenic  and  the  other  an  equivalent  quantity  of 
phosphorus.  Seveial  other  similar  groups  occur,  and  while  their  stu- 
dy is  of  great  importance  to  the  chemist,  their  existence  should  serve 
as  a  caution  to  the  mineralogist,  not  to  place  exclusive  reliance  on  crys- 
tallographic  character. 

In  some  instances  certain  groups  of  crystals  approximate  in  their 
forms  without  becoming  identical.  To  this  approximation  the  term 
plesiomorphism,  has  been  applied. — An  illustration  occurs  in  the  sul- 
phates of  strontia  and  baryta,  the  primary  forms  of  both  salts  are 
rhombic  prisms,  very  similar  to  each  other  ;  but  on  measuring  the 
inclination  of  corresponding  sides  in  each  prism,  the  difference  is  found 
to  exceed  two  degrees.  The  scope  of  this  work  forbids  a  more  detail- 
ed view  of  these  subjects,  and  I  would  therefore  refer  those  who  are 
desirous  of  a  full  account  of  the  present  state  of  our  knowledge  upon 
the  subject  of  isomorphism,  and  the  allied  branches  of  enquiry,  to  Mr. 
J.  F.  W.  Johnston  s  Report  on  Chemistry,  made  in  1832,  to  the  British 
Association  for  the  advancement  of  Science. 

It  is  of  great  importance  in  the  examination  of  crystals  to  measure 
their  angles  with  precision  ;  for  this  purpose  an  instrument  has  been 
invented,  called  a  goniometer,  of  which  there  are  two  kinds,  the  com- 
mon arid  the  reflective. 

The  reflective  goniometer,  invented  by  Dr.  Wollaston,  is  the  most 
useful  of  these  instruments.  It  enables  us  to  determine  the  angles 
even  of  minute  crystals,  with  great  accuracy  :  a  ray  of  light  reflect- 
ed from  the  surface  of  the  crystal  being  employed  as  radius,  instead  of 
the  surface  itself. — See  Phillips'  Introduction  to  Mineralogy,  and  Brandt's 
Chemistry. 

REFERENCES — On  Cohesion — Muschenbroecti 's  Experiments  on  the  cohe- 
sive force  of  solid  bodies,  in  Thomson  s  Chem.  iii.  94.  On  the  means  em- 
ployed by  the  chemist  to  prepare  the  particles  of  bodies  for  chemical  action, 
in  ChaptaVs  Chem.  applied  to  the  Arts,  i.  51.  Boscovich's  explanation 


22  AFFINITY. 

of  the  phenomena  of  cohesion,  in   Thomson's   Chem.   iii.  96.    Arnott's 
Physics. 

On  Crystallography — Plauy  Traite  de  Cristallo  graphic,  i.  Brooke's 
Introduction  to  Crystallography.  Clcavcland's  Mineralogy.  Phillips' 
Introduction  to  Mineralogy.  Gorham's  Chemistry,  i.  Moh's  Mintralo- 
gy,  i.  Leblanc's  method  of  obtaining  large  artificial  crystals,  in  Thomson's 
Chemistry,  iii.  98.  Some  valuable  directions  for  crystallizing  sails  are 
also  to  be  found  in  the  Encyclopedia  Briitannica,  iv.  443.  Remarks  upon 
DanieWs  theory  of  Crystals,  Ann.  of  Phil.  xi.  125,  199,  287. 

SECTIOiN  II. 
AFFINITY. 

SYN.  Chemical  Affinity— Chemical  Attraction— Heterogeneous  Attrac- 
tion. 

If  oil  and  water,  or  water,  oil  and  mercury,  be  agitated  together, 
they  do  not  act  on  each  other,  but  soon  separate  and  exhibit  their  ori- 
ginal characters ;  they  do  not  combine  and  have  no  affinity  for  each 
other.  But  if  olive  oil  and  a  solution  of  potassa  be  agitated  together, 
they  form  a  milky  fluid  in  which  neither  of  them  is  recognized ;  they 
unite  and  form  a  chemical  combination  :  and  bodies  which  unite 
chemically  are  said  to  have  an  affinity  for  each  other,  and  those  which 
do  not  unite  under  any  circumstances  in  which  they  have  been  placed, 
are  correctly  said  to  have  no  affinity  for  each  other. 

Affinity  is  defined  to  be  that  force  by  which  are  united  the  particles 
or  atoms  of  bodies  of  different  kinds.  Like  cohesion,  it  is  only  effec- 
tive at  insensible  distances  ;  it  is  mutual  and  reciprocal  between  those 
bodies  which  it  combines — thus  A  cannot  be  said  to  have  an  affinity  for 
B,  while  B  has  none  for  A. 

Affinity  produces, 

1.  In  some  cases  a  compound  not  materially  altered  in  its  properties. 
Under  this  proposition,  solution  is  usually  offered  as  an  illustration, 
though  it  may  be  doubted  whether  this  is  a  good  example  of  affinity. 

Solution  is  an  operation  by  which  a  solid  body  combines  with  a  fluid 
in  such  a  manner  that  the  compound  retains  the  form  of  a  permanent 
and  transparent  fluid.  In  this  case  the  fluid  is  termed  a  menstruum. 
Solution  can  easily  be  distinguished  from  a  mere  mechanical  mixture 
or  diffusion  as  follows  : 

Exp.  Diffuse  a  quantity  of  magnesia  in  water,  the  mixture  is  turbid 
and  finally  the  magnesia  is  deposited.  If  to  the  turbid  mixture  a  few 
drops  of  nitric  acid  be  added,  it  will  become  transparent,  and  the  mag- 
nesia can  no  longer  be  separated  by  any  mechanical  process  or  by  rest. 
The  nitrate  of  magnesia  is  held  in  solution  by  the  water. 

Solution  is  promoted, 

a.  By  diminishing  the  cohesion  of  the  particles  of  the  body  to  be  dis~ 
solved. 

Exp.  Place  a  lump  of  marble  in  a  wine  glass,  and  a  small  quantity 
of  the  same,  previously  reduced  to  powder  in  another ;  pour  upon 
each,  dilute  muriatic  acid  ;  the  powdered  marble  will  dissolve  much 
more  rapidly  than  the  solid  lump. 


AFFINITY.  23 

b.  By  mechanical  agitation. 

Exp.  Put  a  crystal  of  tartaric  acid  into  a  wine  glass  containing  in- 
fusion of  litmus  or  of  cabbage.  The  acid  if  left  at  rest,  produces  only 
a  slight  effect  in  its  immediate  vicinity,  but  if  the  liquor  be  stirred,  the 
whole  will  become  red. 

c.  By  heat. 

There  are  a  few  exceptions  to  this  statement  which  have  already  been 
adverted  to. 

In  most  cases  of  solution  there  is  a  certain  point  at  which  the  force 
of  affinity  between  the  solid  and  fluid  will  be  balanced  by  the  cohesion 
of  the  solid,  and  beyond  which  solution  will  not  proceed :  this  point 
is  called  saturation,  and  the  resulting  compound  a  saturated  solution. 

2.  Affinity  produces  in  most  cases  a  compound  zohose  prcpei'ties  differ 
essentially  from  those  qftfte  components. 

Exp.  Burn  phosphorus  in  oxygen  gas  or  atmospheric  air,  the  result- 
ing compound  is  phosphoric  acid. 

Exp.  Pass  atmospheric  air  or  oxygen  gas  into  a  vessel  of  nitric  ox- 
ide ;  the  resulting  compound  is  nitrous  acid. 
Affinity  sometimes  also  produces, 

3.  A  change  of  state. 

Exp.  Two  glass  vessels,  one  rilled  with  ammoniacal  gas,  and  the 
other  with  muriatic  acid  gas,  when  brought  into  contact  produce  solid 
muriate  of  ammonia. 

Exp.  To  a  solution  of  muriate  or  nitrate  of  lime  add  sulphuric  acid  ; 
tolid  sulphate  of  lime  will  be  formed. 

Exp.  Crystals  of  sulphate  of  soda  and  nitrate  of  ammonia  triturated 
together  become  a  liquid. 

Exp.  Gunpowder,  when  exploded,  is  resolved  into  various  gases. 

4.  A  change  of  colour. 

Exp.  Add  liquid  ammonia  to  a  solution  of  nitrate  or  sulphate  of  cop- 
per—a  rich  blue  colour  is  produced.  A  few  drops  of  sulphuric  acid 
render  it  colourless. 

Exp.  Sulphate  of  copper  and  acetate  of  lead  rubbed  together  in  a 
mortar  assume  a  green  colour. 

Exp.  A  few  drops  of  tincture  of  galls  added  to  a  very  dilute  so- 
lution of  sulphate  of  iron  produce  a  deep  black. 

In  each  of  these  cases,  the  change  of  colour  is  owing  to  the  forma- 
tion of  a  new  chemical  compound. 

5.  A  change  in  specific  gravity  and  temperature. 

Exp.  Sulphuric  acid  and  water  when  combined  have  the  specific  grav- 
ity of  the  compound  greater  than  that  of  the  mean. 

Exp.  Surround  a  phial  with  some  tow  and  place  a  piece  of  phospho- 
rus within  the  tow  and  against  the  phial.  The  phial  being  half  full  of 
water,  add  a  small  quantity  of  sulphuric  acid  ;  the  heat  produced  will 
be  sufficient  to  fire  the  phosphorus. 

6.  Intense  ignition. 

Exp.  Add  a  few  drops  of  sulphuric  acid  to  a  mixture  of  chlorate  of 
potash  and  sugar. 


24  AFFINITY. 

Exp.  Add  sulphuric  acid  to  phosphorus  and  chlorate  of  potash  un- 
der water. 

There  are  several  circumstances  which  influence  and  modify  the  op- 
eration of  affinity. 

1.  A  previous  state  of  combination.      This  generally  diminishes,  and 
often  prevents  chemical  action. 

2.  Cohesion.     This,  as  has  been  already  remarked,  often  acts  as  an 
antagonist  power  to  [chemical  affinity.     Hence  the  utility  of  mechani- 
cal processes  which  diminish  this  force.     Solid  antimony  is  but  slowly 
acted  upon  by  chlorine  gas,  but  when  in   the   state  of  fine  powder, 
it  takes  fire  as  soon  as  it  touches  the  gas.     Hence  also  liquidity  fa- 
vours chemical  action,  the  cohesive  power  being  comparatively  so  tri- 
fling as  to   present   no   appreciable  barrier  to   affinity.      There   are, 
however,  some  instances  in  which  two  solids  act  chemically  on  each 
other. 

3.  Caloric.  This  has  a  very  important  influence  over  chemical  ac- 
tion :  sometimes  increasing  it,  at  other  times  destroying  or  subverting 
it.     Thus  bodies  which  unite  at  one  temperature  refuse  to  combine  or 
remain  combined  at  another  temperature.      Lead  shavings  do  not  de- 
compose cold  nitric  acid,  but  when  heat  is  applied,  rapid  decomposition 
ensues.     An  increase  of  temperature  favours  chemical  action  by  its  ef- 
fect in  overcoming  the  force  of  cohesion  ;  but  this  explanation  is  not  of 
universal  application. 

4.  The  electric  state  of  bodies.      Those  bodies  which  are  in  the  same 
electric  state  do  not  combine,  those  in  different  electric  states  do  com- 
bine.    Indeed   so  intimate  is  the  connexion  which  subsists  between 
electricity  and  chemical  action,  that  they  have  been  supposed  by  some 
to  depend  upon  the  same  power.     Hence  the  Electro -Chemical  Theory 
of  Davy,  which  will  be  more  fully  noticed  hereafter. 

5.  Specific  gravity.     When  two  bodies  have  different  specific  gravi- 
ties, they  tend  to  separate.     If  their  affinity  is  very  feeble,  they  can 
not  be  made  to  combine.     Oil  and  water,  and  mercury  and  water,  are 
familiar  examples.     The  influence  of  specific  gravity  over  chemical  ac- 
tion is,  however,  quite  limited. 

6.  The  intervention  of  a  third  body.     This   sometimes  increases   and 
sometimes   destroys   chemical   action.      Oil   and   water  are  made  to 
unite  upon  the  addition  of  an  alkali.     Alcohol  added  to  a  saturated 
solution   of  sulphate  of  soda  or  nitrate  of  potassa  combines  with  the 
water,  and  the  crystallization  of  the  salt  instantly  takes  place.     This 
has  been  called  disposing  or  predisposing  affinity,  which  to  say  the  least, 
is  an  extremely  vague  term. 

7.  Mechanical  action  or  compression.  This  frequently  modifies 
chemical  action  in  a  great  degree,  particularly  in  the  case  of  gases  and 
liquids.  Thus  water  when  under  high  pressure  combines  with  a  greater 
quantity  of  carbonic  acid  than  when  the  pressure  is  less.  The  com- 
pound of  carbonic  acid  and  lime,  known  under  the  name  of  chalk,  may 
be  decomposed  by  the  simple  application  of  an  intense  heat ;  but  under 
strong  pressure,  a  heat  may  be  applied  sufficient  to  melt  the  chalk 
without  expelling  the  carbonic  acid.  It  is  this  principle,  (the  influ- 
ence of  pressure  in  opposing  chemical  decomposition,)  that  is  the 
foundation  of  Dr.  Hutton's  ingenious  Theory  of  the  Earth.—  Henry's 
Chem.  llth  ed.  i.  65. 


AFFINITY.  25 

8.  Quantity  of  matter  or  mass.  The  influence  of  quantity  of  matter 
over  affinity  appears  to  be  now  generally  admitted.  If  one  body  A, 
unites  with  another  body  B,  in  several  proportions,  that  compound  will 
be  the  most  difficult  of  decomposition  which  contains  the  smallest 
quantity  of  B.  Of  the  three  oxides  of  lead,  for  instance,  the  peroxide 
parts  most  easily  with  its  oxygen  by  the  action  of  caloric  ;  a  higher 
temperature  is  required  to  decompose  the  deutoxide,  and  the  protoxide 
will  bear  the  strongest  heat  of  our  furnaces,  without  losing  a  particle  of 
its  oxygen. 

The  influence  of  quantity  over  chemical  attraction  may  be  further 
illustrated  by  the  phenomena  of  solution.  When  equal  weights  of  a 
soluble  salt  are  added  in  succession  to  a  given  quantity  of  water,  which 
is  capable  of  dissolving  almost  the  whole  of  the  salt  employed,  the  first 
portion  of  the  salt  will  disappear  more  readily  than  the  second,  the 
second  than  the  third,  the  third  than  the  fourth,  and  so  on.  The  af- 
finity of  the  water  for  the  saline  substances  diminishes  with  each  ad- 
dition, till  at  last  it  is  weakened  to  such  a  degree  as  to  be  unable  to 
overcome  the  cohesion  of  the  salt.  The  process  then  ceases  and  a  satu- 
rated solutiou  is  obtained. 

Quantity  of  matter  is  employed  advantageously  in  many  chemical 
operations.  If,  for  instance,  a  chemist  is  desirous  of  separating  an 
acid  from  a  metallic  oxide,  by  means  of  the  superior  affinity  of  potassa 
for  the  former,  he  frequently  uses  rather  more  of  the  alkali  than  is 
sufficient  for  neutralizing  the  acid.  He  takes  the  precaution  of  em- 
ploying an  excess  of  alkali,  in  order  the  more  effectually  to  bring  eve- 
ry particle  of  the  substance  to  be  decomposed  in  contact  with  the  de- 
composing agent. 

But  Berthollet  has  attributed  a  much  greater  influence  to  quantity 
of  matter.  His  views,  however,  do  not  appear  to  be  supported  by 
facts. — Berthollet  Chem.  Stat.  Turner's  Chem.  Davy's  Elements. 

Affinity  is  of  two  kinds — 

1.  SIMPLE. 

2.  ELECTIVE. 

Simple  affinity  is  the  union  of  the  constituent  atoms  of  a  compound 
without  causing  decomposition.  It  is  sometimes  also  called  combina- 
tion. Thus  the  combustion  of  carbon  in  oxygen  gas  produces  by  the 
mere  union  of  these  two  elements  carbonic  acid.  So  also  sulphur- 
ic acid  and  potassa  by  mere  combination  form  sulphate  of  potassa. 

Elective  Affinity  is  of  two  kinds,  simple  and  compound,  or  single  and 
double. 

An  important  law  of  affinity,  and  which  indeed  is  the  basis  of  almost 
all  chemical  theory,  is  that  the  same  body  has  not  the  same  force  of 
affinity  towards  a  number  of  others,  but  attracts  them  unequally. 
Thus  when  sulphuric  acid  is  added  to  a  solution  of  nitrate  of  lime, 
(composed  of  nitric  acid  and  lime,)  the  lime  leaves  the  nitric  acid  and 
combines  with  the  sulphuric,  forming  a  sulphate  of  lime.  This  is  an 
example  of  what  is  termed  in  chemistry,  a  simple  decomposition.  The 
lime  in  this  case  is  considered  as  making  an  election  of  the  sulphuric 
acid  in  preference  to  the  nitric  ;  and  this  affinity  has  been  called  single 
elective  affinity.  When  one  of  the  substances  falls  down  in  the  state  of 
powder,  it  is  termed  a  precipitate. 

Other  illustrations  of  single  elective  affinity. 

Exp.  Add  sulphuric  acid  to  muriate  of  soda,  muriatic  acid  is  disen- 
gaged and  sulphate  of  soda  remains. 


26  AFFINITY. 

Exp.  To  a  solution  of  nitrate  of  silver  add  mercury  ;  the  nitric  acid 
will  in  a  short  time  leave  the  silver  and  combine  with  the  mercury. 
To  the  nitrate  of  mercury  thus  formed,  add  lead,  the  nitric  acid  will 
leave  the  mercury  and  unite  with  the  lead.  To  this  last  add  copper, 
and  nitrate  of  copper  will  be  produced. 

Upon  the  discovery  of  this  important  law,  it  occurred  to  Geoffrey,  a 
French  chemist,  that  tables  might  be  constructed,  which  should  ex- 
hibit the  relative  forces,  of  the  attraction  of  any  body  towards  others. 
The  substance,  whose  affinities  are  to  be  thus  expressed,  is  merely 
placed  at  the  head  of  a  column  separated  from  the  rest  by  a  horizontal 
line.  Beneath  this  line  are  arranged  the  different  substances  for  which 
it  has  any  attraction,  in  an  order  corresponding  with  that  of  their  res- 
pective forces  of  affinity  ;  the  substance  which  it  attracts  most  power- 
fully being  placed  nearest  to  it,  and  that  for  which  it  has  the  least  affin- 
ity at  the  bottom  of  the  column.  The  following  series  exhibiting  the 
affinities  of  sulphuric  acid  for  the  alkalies  and  alkaline  earths,  will  serve 
as  an  example. 

SULPHURIC  ACID. 


BARYTA, 
STRONTIA, 

POTASSA, 

SODA, 
LIME, 
AMMONIA, 
MAGNESIA. 

Double  Elective  Affinity,  This  kind  of  affinity  takes  place  when 
two  bodies,  each  consisting  of  two  principles  are  presented  to  each 
other,  and  mutually  exchange  a  principle  of  each  ;  by  which  means 
two  new  bodies  or  compounds,  are  produced,  of  a  different  nature 
from  the  original  compounds.  In  this  case  it  frequently  happens, 
that  the  compound  of  two  principles  cannot  be  destroyed,  either  by 
a  third  or  a  fourth  separately  applied  ;  whereas  if  this  third  and  fourth 
be  combined,  and  placed  in  contact  with  the  former  compound,  a 
decomposition  or  change  of  principles  will  ensue.  Thus  when  lime- 
water  is  added  to  a  solution  of  sulphate  of  soda,  no  decomposition 
happens,  because  sulphuric  acid  attracts  soda  more  strongly  than  it 
does  lime.  If  nitric  acid  be  applied  to  the  same  compound,  still  its 
principles  remain  undisturbed,  because  the  sulphuric  acid  attracts  soda 
more  strongly  than  the  nitric.  But  if  lime  and  nitric  acid  previously 
combined,  be  mixed  with  the  sulphate  of  soda,  a  double  decomposition 
is  effected  and  two  new  compounds  are  produced.  These  changes 
may  be  expressed  by  the  following  diagram,  contrived  by  Bergman. 

Nitrate  of  Soda. 


Sulphate  \  Soda.  Nitric  acid.  /  Nitrate 

of         <  V       of 

Soda       /  Sulphuric  acid.  Lime.  \    Lime. 

Sulphate  of  Lime. 

On  the  outside  of  the  vertical  brackets  are  placed  the  original  com- 
pounds, (sulphate  of  soda  and  nitrate  of  lime,)  above  and  below  the 


LAWS   OF   COMBINATION.  27 

horizontal  lines,  the  new  compounds  produced,  (nitrate  of  soda  and 
sulphate  of  lime, )  the  upper  line  being  straight  indicates  that  the  ni- 
trate of  soda  remains  in  solution,  the  dip  of  the  lower  line,  that  the  sul- 
phate of  lime  is  precipitated. 

A  piece  of  sheet  lead  immersed  in  a  solution  of  sulphate  of  zinc  pro- 
duces no  change,  because  the  sulphuric  acid  has  a  stronger  affinity  for 
the  zinc  than  for  the  lead.  Neither  does  acetic  acid  produce  any 
change.  But  when  acetate  of  lead  is  added,  two  new  compounds,  viz. 
sulphate  of  lead  and  acetate  of  zinc  are  the  result. 

In  the  above  cases,  as  in  many  others,  we  can  easily  explain  the  de- 
compositions which  take  place.  There  are  two  distinct  sets  of  affini- 
ties, one  tending  to  prevent  any  change  of  composition,  as  between 
the  sulphuric  acid  and  the  soda  in  the  former  case,  and  between  the 
nitric  acid  and  the.  lime;  termed  by  Kirwan  the  quiescent  affinities. 
Another  set  tending  to  produce  a  decomposition  as  between  the  nitric 
acid  and  the  soda,  and  the  sulphuric  acid  and  the  lime,  are  termed  the 
divellent  affinities,  and  which  in  this  case  are  the  most  powerful.  But 
other  cases  of  double  decomposition  cannot  be  explained  in  this  man- 
ner. As  for  instance,  carbonate  of  baryta  and  sulphate  of  potassa  mu- 
tually decompose  each  other. — 1?.  Phillips  Quart.  Jour.  i.  80.  Dulong 
in  Phil.  Magazine,  41. 

REFERENCES.  The  article  *  Chemical  Decomposition/  in  the  Supplement 
o  the  Encyclopedia  Britannica^  by  Dr.  Thomson.  Turners  Chemistry,  sec- 
tion on  Affinity.  Murray's  Chemistry,  Book  I,  on  Attraction.  Davy's  Ele- 
tments  of  Chemical  Philosophy.  Ure's  Chemical  Dictionary,  Art.  Attrac- 
tion. Branded  History  of  Chemistry.  Henrys  C  Ministry,  llth  ed.  1. 
Bishop  Watson  on  the  various  phenomena  attending  the  solution  of  salts,  in 
Phil.  Trans.  1770,  235,  and  in  Chemical  Essays,  r.  43.  Gay  Lussac  on  the 
solubility  of  the  salts  in  water.  Ann.  of  Phil.  xv.  1- 

SECTION  III. 

OP    THE    PROPORTIONS    IN    WHICH    BODIES    COMBINE  ;    AND    OF 
THE  ATOMIC  THEORY. 

In  the  chemical  combination  of  bodies  with  each  other,  the  follow- 
ing circumstances  deserve  to  be  mentioned. 

I.  Some  bodies  unite  in  all  proportions  ;  for  example,  water  and  sul- 
phuric acid,  and  water  and  alcohol. 

II.  Other  bodies  combine  in  all  proportions,  as  far  as  a  certain  point, 
beyond  which,  combination  no  longer  takes  place.     Thus  water  will  take, 
up  successive  portions  of  common  salt,  until  at  length  it  becomes 
incapable  of  dissolving  any  more.     In  cases  of  this  sort,  as  well  as  in 
those  included  under  the  first  head,  combination  is  weak  and  easily 
destroyed,   and  the  qualities,   which  belonged  to  the  components  in 
their  separate  state,  continue  to  be  apparent  in  the  compound. 

It  is  necessary  however,  to  remark,  that  these  two  deductions, 
though  they  appear  to  be  warranted  by  a  general  survey  of  the  phe- 
nomena, are  not  absolutely  and  strictly  true  ;  for  though  some  acids, 
for  instance,  appear  to  unite  with  water  in  every  proportion,  yet  there 
are  certain  relative  qualities  of  water  and  acid  which  form  the  most 
energetic  compounds,  distinguished  by  their  permanency  and  peculiar 
properties — Henry's  Chem.  i.  43. 


28  LAWS    OF   COMBINATION. 

III.  Some  bodies  unite  in  one  proportion,  or  in  a  few  proportions  only. 
Chlorine  and  hydrogen  combine  in  no  other  proportions  than  those 
constituting  muriatic  acid.  On  the  other  hand,  carbon  and  oxygen 
unite  in  two  proportions  ;  oxygen  and  nitrogen  in  five  proportions, 
&c.  The  greatest  number  of  compounds  that  any  two  substances  are 
known  to  produce,  is  six,  if  we  except  those  noticed  in  the  preceding 
paragraphs. 

The  combination  of  bodies  that  unite  in  this  manner,  is  regulated 
by  the  following  laws  : 

I.  The  composition  of  bodies  is  fixed  and  invariable.     A  compound 
substance   so  long  as  it  retains  it  characteristic  properties,  must  al- 
ways consist  of  the  same  elements  united  together  in  the  same  pro- 
portion. Muriatic  acid,  for  example,  is  always  composed  of  35.45*  parts 
by  weight  of  chlorine,  and  one  of  hydrogen  ;  no  other  elements  can 
form  it,  nor  can  its  own  elements  form  it  in  any  other  proportion. 
Water,  in  like  manner,  is  formed  of  1    part  of  hydrogen  and  8  of 
oxygen  ;  and  were  these  two  elements  to  unite  in  any  other  propor- 
tion, some  new  compound,  different  from  water,  would  be  the  product. 
The  same  observation  applies  to  all  other  substances,  however  com- 
plicated,  and  at  whatever  period   they  were  produced.     Thus,  sul- 
phate of  baryta,  whether  formed   ages  ago  by  the  hand  of  nature,  or 
quite  recently *by  the  operations  of  the  chemist,  is  always  composed 
of  40  parts  of  sulphuric  acid  and  76.7  of  baryta.     This  law,  in  fact,  is 
universal  and  permanent.     Its  importance  is  equally  manifest.     It  is 
the  essential  basis  of  chemistry,  without  which  the  science  itself  could 
have  no  existence. — Turner's  Chem. 

II.  The  relative  quantities  in  which  bodies  unite,  may  be  expressed  by 
proportional  numbers.     Thus  8  parts  of  oxygen  unite  with  one  part  of 
hydrogen,  16  of  sulphur,  35.45  of  chlorine,  40  of  selenium,  and  108 
parts  of  silver.     Such  are  the  quantities  of  these  five  bodies  which  are 
disposed  to  unite  with  8  parts  of  oxygen  ;  and  it  is  found  that  when 
they  combine  with   one  another,  they  unite  either  in  the  proportion 
expressed  by  those  numbers,  or  in  multiples  of  them  according  to  the 
third  law  of  combination.     Thus  sulphuretted  hydrogen  is  composed 
of  1  part  of  hydrogen  and  16  of  sulphur,  and  bisulphuretted  hydrogen, 
of  one  part   of  hydrogen  to  3'2  of  sulphur ;  35.45  of  chlorine  unite 
with  one  of  hydrogen,  16  of  sulphur,  and  108  of  silver,  and  40  .parts 
of  selenium  with  1  of  hydrogen,  and  16  of  sulphur. 

From  these  examples  it  is  manifest,  that  bodies  unite  according  to 
proportional  numbers  ;  and  hence  has  arisen  the  use  of  certain  terms, 
such  as  proportions,  combining  proportions,  proportionals,  or  equiva- 
lents to  express  them.  Thus  the  combining  proportions  of  the  sub- 
stances just  alluded  to  are — 

Hydrogen 1 

Oxygen 8 

Sulphur 16 

Chlorine 35.45 

Selenium 40 

Silver  ........  108 

This  law  also  applies  to  compound  bodies.  Thus  water  is  composed 
of  one  proportional  or  8  parts  of  oxygen,  and  one  proportional  or  1 

*  I  adopt,  vrith  few  exceptions,  the  equivalent  numbers  of  Dr.  Turner. 


LAWS   OF   COMBINATION.  29 

part  of  hydrogen,  and  hence  its  combining  proportion  is  9.  The  pro- 
portional of  sulphuric  acid  is  40,  because  it  is  a  compound  of  one 
proportion  or  16  parts  of  sulphur,  and  three  proportions  or  24  parts  of 
oxygen.  And  so  in  all  other  cases  not  only  of  compounds  but  of  two 
"elements  of  salts;  the  latter  of  which  indeed,  furnish  the  most  strik- 
ing illustrations  of  this  subject. 

III.  When  one  body  A  unites  with  another  body  E  in  two  or  more  pro- 
portions, the  quantities  of  the  latter,  united  to  the  same  quantity  of  the 
former,  bear  to  each  other  a  very  simple  ratio.  These  ratios  of  B  may 
in  all  cases  be  represented  by  one  or  other  of  the  two  following  se- 
ries : — 

1st.— A  unites  with  1,  2,  3,  4,  5,  &c.  of  B. 
2d.— A  unites  with  1,  1  1-2,  2,  2  1-2,  &c.  of  B. 

The  following  table  exemplifies  the  first  series. — 

Water  is  composed  of        ...  Hydrogen  1  .     .  Oxygen  8 )  1 

Deutoxide  of  Hydrogen    ...          Do.  1  .     .  Do.  16  $  2 

Carbonic  Oxide Carbon  6  .     .  Do.  8)1 

Carbonic  Acid Do.  6  .     .  Do.  16  }  2 

Nitrous  Oxide Nitrogen  14  ..  Do.  16 ^  1 

Nitric  Oxide Do.  14  .     .  Do.  16  |  2 

Hyponitrous  Acid Do.  14  ..  Do.  24  }  3 

Nitrous  Acid        ......          Do.  14  ..  Do,  32  I  4 

Nitric  Acid Do.  14  ..  Do.  40  j  5 

It  will  be  observed  that  in  all  the  above  cases  the  ratios  of  the  oxy- 
gen are  expressed  by  whole  numbers.  In  water  the  hydrogen  is 
combined  with  half  as  much  oxygen  as  in  the  deutoxide  of  hydrogen, 
and  hence  the  ratio  is  as  one  to  two.  The  same  may  be  said  of  car- 
bonic oxide  and  carbonic  acid.  In  the  compounds  of  nitrogen  and 
oxygen  the  latter  is  in  the  ratio  of  1,2,  3,  4,  &  5.  This  ratio  also 
extends  to  the  combinations  of  combustibles  with  each  other  and  to 
the  salts.  It  may  be  illustrated  by  a  very  simple  experiment,  first 
made  by  Dr.  Wollaston  ;  let  a  given  weight  of  bicarbonate  of  potassa 
be  thrown  into  a  tube  over  mercury,  and  diluted  sulphuric  acid  suffi- 
cient to  cover  it,  be  introduced  into  the  tube,  when  a  certain  volume  of 
carbonic  acid  gas  will  be  disengaged  ;  let  an  equal  weight  of  the 
carbonate  be  treated  in  the  same  way  and  it  will  be  found  to  give  off 
exactly  half  as  much  carbonic  acid  gas. 

The  second  series  is  exemplified  in  the  following  compounds  : 

Protoxide  of  iron  consists  of         Iron          28  Oxygen       8)1 

Peroxide        ....         Do.          28  Do.  12  $  H 

Protoxide  of  lead  .         .         .      Lead        103.5  Do.         8  )  I 

Deutoxide     .         .         .         .         Do.         103.5  Do.  12  >  H 

Peroxide        .        .         .         .         Do.         103.5  Do.  16)2"" 

Arsenious  Acid    .         .         .    Arsenic        37.7  Do.  12  )  H 

Arsenic  Acid         ...         Do.          37.7  Do.  20  $  2| 

Hypo-Phosphorous  Acid       .  Phosphorus    15.7  Do.          4  )  £ 

Phosphorous  Acid        .         .          Do.           15.7  Do.  12j>H 

Phosphoric  Acid           .         .          Do.          15.7  Do.  20  )  2| 

Both  of  these  series,  which  together  constitute  the  third  law  of  com- 
bination, as  Dr.  Turner  remarks,  result  naturally  from  the  operation 
of  the  second  law.  The  first  series  arises  from  one  proportion  of  a 


30  LAWS   OF   COMBINATION. 

body  uniting  with  1,  2,  3  or  more  proportions  of  another  body.  The 
second  series  is  a  consequence  of  two  proportions  of  one  substance 
combining  with  3,  5,  or  more  proportions  of  another.  Thus  if  two 
proportions  of  phosphorus  unite  both  with  3  and  5  proportions  of. 
oxygen,  we  obtain  the  ratio  of  1  1-2  to  2  1-2  ;  and  should  one  propor- 
tion of  iron  combine  with  one  of  oxygen,  and  another  compound  be 
formed  of  two  proportions  of  iron  to  three  of  oxygen,  then  the  oxygen 
united  with  the  same  weight  of  iron  would  have  the  ratio,  as  in  the 
table,  of  1  to  1  1-2.  And  the  compounds  of  lead  and  phosphorus  with 
oxygen,  afford  examples  of  the  same  kind.  Turner's  Chem.  4th  ed. 

IV.  Gases  or  airs  unite  in  the  most  simple  ratios  of  volume  or  bulk. 
This  important  fact  was  discovered  by  Gay  Lussac.     Thus  1  volume 
unites  to  1,  or  1  to  2,  or  1  to  3,  &e.     In  combination  by  weight  there 
is  no  simple  multiple  ratio  between  the  weight  of  the  elements  in  the 
first  compound  ;  the  oxygen  for  example ,  is  not  equal  to,  or  twice  or 
thrice,  &c.  the  weight  of  the  nitrogen  in  nitrous  oxide,  or  of  carbon  in 
carbonic  oxide  ;  it  is  only  when  there  is  a  second  compound  formed 
of  the  same  elements,  that  the  new  proportions  of  the  body  which  has 
been  added,  become  a    multiple  of  the  first.     But  in  combinations  by 
volume,  the  bulk  of  one  of  the  gases  in  the  first,  as  well  as  in  the  other 
compounds,  is  always  equal  to,  or  is  some  multiple  of  that  of  the 
other :   thus, 

100  of  oxygen  combine  with  200  hydrogen. 

100  ammonia         "         "          50  carbonic  acid. 

100  ammonia         "         "        100  carbonic  acid. 

100  nitrogen          "         "          50,100,150,200. 

and  250  volumes  of  oxygen. 

Another  curious  fact  established  by  Gay  Lussac  is  that  the  diminu- 
tion of  bulk,  which  gases  frequently  suffer  in  combining  is  also  in  a 
very  simple  ratio.  Thus  the  four  volumes  of  which  ammonia  is  con- 
stituted, (3  volumes  of  hydrogen  and  1  of  nitrogen,)  contract  to  one 
half  or  two  volumes  when  they  unite.  There  is  a  contraction  to  two- 
thirds  in  the  formation  of  nitrous  oxide,  to  1  half  in  the  formation  of 
sulphuretted  hydrogen,  and  to  1  half  in  that  of  sulphurous  acid 
&c.  [For  a  more  full  exposition  of  this  law  see  Henry's  Chem. 
i.  55.] 

V.  The  respective  quantities  of  any  number  of  alkaline,  earthy  or  me- 
tallic bases  required  to  saturate  a  given  quantity  of  any  add,  are  always 
in  the  same  ratio  to  each  other,  to  ichatsoevcr  acid  they  be  applied. 

This  law  appears  to  have  been  discovered  by  Richter  of  Berlin,  in 
1792,  and  has  been  fully  confirmed  by  succeeding  chemists. 

For  an  illustration  of  it  let  us  take  potassa  and  soda  for  the  bases, 
and  sulphuric  acid  for  the  acid.  Having  found  by  experiment  that 
tv/o  parts  of  soda  will  saturate  as  much  of  the  acid  as  three  of  the 
potash,  their  power  of  saturating  every  other  acid  is  in  the  ratio  of  two 
to  three.  Thus  if  we  should  ascertain  by  experiment  that  it  required 
4  parts  of  soda,  to  neutralize  any  given  quantity  of  nitric  acid,  we 
should  know  without  experiment  that  it  would  require  6  parts  of 
potash  to  neutralize  the  same  amount  of  nitric  acid.  Two  parts 
of  soda  are  therefore  said  to  be  equivalent  to  three  of  potash.  This 
rale  applies  as  well  to  all  the  acids  as  to  the  bases,  and  greatly  facili- 
tates chemical  investigations.  Thus  if  we  have  100  bases  and  50  acids, 
we  have  only  to  apply  each  of  these  bases  to  any  one  of  the  acids,  and 
one  of  the  bases  to  all  the  acids,  to  ascertain  the  amount  of  all  the 


LAWS   OF   COMBINATION.  31 

other  bases  necessary  to  saturate  all  the  acids.  Hence  we  need  only 
perform  149  experiments  instead  of  5000  which  we  should  be  obliged 
to  do  without  a  knowledge  of  this  law. 

By  arranging  the  numbers  indicating  the  relative  combining  weights 
or  equivalent  quantities  of  different  substances  on  a  moveable  scale, 
and  writing  against  them  the  names  of  the  substances  they  respectively 
represent,  Dr.  Wollaston  constructed  a  Scale  of  Chemical  equivalents, 
an  instrument  stamped  with  the  accuracy  and  ingenuity  of  its  author, 
and  of  great  value  to  the  practical  chemist. — Phil.  Trans.  1814. 

In  this  instrument  the  slide  is  a  line  of  numbers  on  which  equal  dis 
tances  denote  equal  ratios.  The  distance  between  50  and  an  100,  for 
example,  is  the  same  as  that  between  1  and  2,  because  50  :  100  :  1  :  2. 
Opposite  to  the  numbers  on  this  scale,  are  written  the  names  of  the 
bodies  of  which  the  numbers  themselves  are  the  equivalents  ;  then 
the  distances  between  these  bodies  are  in  like  manner  the  measures 
of  the  ratios  of  their  combining  quantities,  and  will  be  the  same  with 
the  distances  between  the  numbers.  But  the  chief  value  of  the  ar- 
rangement is,  that  by  means  of  the  slide,  we  can  at  once  solve  a 
great  number  of  cases  which  arise  out  of  combinations  and  decompo- 
sitions, the  solution  of  which  in  the  ordinary  way  would  require  a 
tedious  number  of  computations. 

As  the  proportional  numbers  merely  express  the  relative  quantities 
of  different  bodies  which  unite  together,  it  is  of  no  consequence  what 
figures  are  employed  to  express  them,  provided  the  relation  is  strictly 
observed :  Thus  Dr.  Thomson  makes  oxygen  1,  so  that  hydrogen  is 
8  times  less  than  unity,  or  0.125,  carbon  0.75,  and  sulphur  2.  Dr. 
Wollaston  in  his  scale  of  equivalents,  fixes  oxygen  at  10,  by  which 
hydrogen  is  1.25,  carbon  7.5,  &c.  But  the  greatest  number  of  chem- 
ists call  hydrogen  unity  and  therefore  oxygen  8.  This  is  much  the 
most  simple,  and  has  been  adopted  in  the  scale  of  equivalents  con- 
structed by  Professor  Henry  and  myself,  and  also  in  the  present  work. 
A  circular  table  of  chemical  equivalents  is  described  in  Brande's  Jour. 
Hi.  391. 

The  utility  of  being  acquainted  with  the  important  laws  which  have 
here  been  given  is  almost  too  manifest  to  require  notice.  Through 
their  means  our  knowledge  of  the  composition  of  bodies  is  much  sim- 
plified. The  exact  quantities  of  bodies  necessary  to  produce  a  desired 
effect  can  also  be  at  once  determined  with  certainty,  and  these  laws 
thus  become  highly  useful  both  in  the  practice  of  the  chemical  arts 
and  in  the  operations  of  pharmacy.  The  same  knowledge,  moreover, 
affords  the  best  guide  to  the  analyst,  by  which  to  judge  of  the  accura- 
cy of  his  results.  Thus  a  powerful  argument  in  favor  of  the  accuracy 
of  an  analysis  is  derived  from  the  correspondence  of  its  results  with 
the  laws  of  chemical  combination.  On  the  contrary,  if  it  form  an  ex- 
ception, it  may  be  considered  doubtful,  and  we  may  hence  be  led  to 
detect  an  error,  which  might  otherwise  have  escaped  notice. 

It  should  be  observed  that  these  laws  are  deduced  from  experiment, 
and  the  student  should  be  careful  to  keep  them  distinct  from  the  theo- 
ry which  has  been  proposed  to  account  for  them.  Whatever  may  be 
the  fate  of  this  theory,  it  cannot  affect  these  laws,  though  the  progress 
of  discovery  may  render  it  necessary  that  they  should  be  modified. 

ATOMIC    THEORY. 

The  foregoing  are  the  principal  facts,  which  the  experimental  ex- 
aminations of  chemical  combinations  and  decompositions  have  un- 


32  ATOMIC   THEORY. 

folded.  To  account  for  these  facts  a  theory  has  been  invented  which 
is  denominated  the  Atomic  Theory ;  which  derives  much  probability 
from  the  complete  solution  it  affords  of  the  laws  of  attraction.  For  the 
full  developement  of  this  theory  we  are  indebted  to  the  labors  of  Mr. 
Higgins  and  Mr.  Dalton. 

The  Atomic  Theory  proceeds  on  the  supposition  that  every  body  is 
an  assemblage  of  minute,  solid  particles,  without  considering  whether 
a  farther  division  of  them  be  possible  or  not.  The  question  of  the  in- 
finite divisibility  of  matter  is  not  therefore  involved  ;  the  theory  only 
assumes  that  matter  is  not,  in  fact  infinitely  divided.  These  undivid- 
ed particles  are  the  atoms  in  question.  It  is  also  assumed  that  these 
atoms  differ  from  each  other  in  weight,  whether  this  difference  is 
owing  to  specific  gravity  or  size,  or  both  together,  is  not  material. — 
Thomson's  First  Pi  in.  v.  1. 

It  is  further  supposed  that  though  we  appear,  when  we  effect  a 
chemical  union,  to  operate  on  masses,  the  combination  only  takes 
place  between  these  ultimate  particles  or  atoms.* 

To  apply  this  theory,  let  us  take  the  compounds  of  nitrogen  and 
oxygen,  which  are  five,  differing  much  from  each  other  ;  viz  :  nitrous 
oxide,  nitric  oxide,  hyponitrous  acid,  nitrous  acid  and  nitric  acid.  If 
we  take  a  given  quantity  of  nitrogen,  say  14  r  grains,  and  combine  it 
with  8  grains  of  oxygen,  we  form  nitrous  oxide  ;  with  8  more,  we  have 
nitric  oxide  ;  with  8 more,  hyponitrous  acid  ;  with  8  more,  nitrous  acid; 
with  8  more,  nitric  acid.  Now  supposing  that  these  several  compounds 
are  formed  by  the  union  of  a  certain  number  of  atoms  of  oxygen,  the 
latter  number  varying  in  the  several  compounds,  the  first  compound  is 
probably  formed  of  an  equal  number  of  atoms  of  each  element.  It  is 
plain  that  one  atom  of  nitrogen  can  combine  with  no  less  than  one 
atom  of  oxygen,  because  the  atoms  are,  by  the  hypothesis,  indivisi- 
ble, or  at  least  undivided.  Nor  is  it  probable,  that,  in  forming  the 
first  compound,  one  atom  of  nitrogen  combines  with  any  more  than 
one  of  oxygen  ;  for  this  union  is  the  most  simple  and  hence  the  most 
natural.  The  first  compound  then  being  formed  of  one  atom  of  ni- 
trogen and  one  of  oxygen,  it  is  plain  that  no  new  compound  can  be 
formed,  until  we  add  at  least  one  atom  of  oxygen  ;  and  hence  the 
reason  is  evident  why  in  all  the  higher  combinations  the  quantity  of 
oxygen  is  just  twice,  or  thrice,  or  four  times  that  in  the  lowest,  there 
being  respectively  just  twice,  or  thrice,  or  four  times  as  many  atoms 
of  oxygen. 

In  cases  where  two  bodies  unite  only  in  one  proportion,  it  is  assum- 
ed that  they  unite  atom  to  atom  ;  and  hence  if  we  determine  the  rela- 
tive weights  of  the  masses,  which  enter  into  combination,  we  can  easi- 
ly determine  the  relative  weights  of  the  atoms ;  the  ratio  being  the 
same.  Thus  chlorine  and  hydrogen  combine  only  in  one  proportion, 
forming  muriatic  acid.  The  volume  of  each  is  the  same,  but  the 
weight  of  the  volume  of  chlorine  is  35.45  times  greater  than  that  of 
the  volume  of  hydrogen  ;  hence  the  atom  of  chlorine  is  to  that  of 
hydrogen  as  35.45  to  1. 


*  An  ingenious  method  of  illustrating  this  theory  has  been  invented  by 
Professor  Hadley  of  the  Medical  College  of  the  Western  District.  Jt  con- 
sists of  a  box  containing  a  number  of  cubical  blocks,  which  are  variously 
colored  to  represent  the  principal  elementary  substances.  By  these  represen- 
tatives of  atoms,  the  laws  of  combination  may  be  strikingly  presented  to  the 
student,  and  many  of  the  more  complex  chemical  decompositions  rendered 
aparent. 


ATOMIC    THEORY.  33 

\ 

The  weight  of  the  atoms  of  all  other  bodies  is  ascertained  in  the 
same  manner.  Thus  an  atom  of  carbon  is  six  times,  and  an  atom  of 
sulphur  16  times  heavier  than  that  of  hydrogen  ;  and  this  is  precisely 
the  reason  why  they  unite  with  each  other  in  the  proportions  express- 
ed by  those  numbers.  What  are  called  proportional  or  equivalent 
numbers,  are  therefore,  in  fact  nothing  else  but  the  relative  weights  of 
atoms.* 

The  two  assumptions,  which  indeed  constitute  the  basis  of  this  the- 
ory, would  be  considered  gratuitous,  were  it  not  for  the  complete 
explanation  which  they  afford  of  the  laws  of  definite  proportions. — 
They  are  further  supported  by  the  fact,  that  the  weight  of  an  atom 
comes  out  the  same  when  deduced  from  different  premises.  This 
theory  is  also  confirmed  by  the  observations  of  Dr.  Wollaston,  in 
his  essay  on  the  finite  extent  of  the  atmosphere.—  [Phil.  Trans.  1822.] 
And  another  argument  which  appears  to  amount  almost  to  demon- 
stration, is  deducible  from  the  peculiar  connexion  noticed  by  Pro- 
fessor Mitscherlich,  between  the  form  and  composition  of  certain 
substances. — Ann.  dc,  Chim.  et  de  Pkys.  xiv.  172,  xix.  350.  and  xxiv. 
264  and  365. 

There  is  a  seeming  objection  to  the  atomic  theory  in  those  cases 
where  one  proportion  of  one  body  combines  with  one  proportion  and 
a  half  of  another.  In  such  cases,  however,  it  is  supposed  that  two 
atoms  of  the  one  are  combined  with  three  atoms  of  the  other,  by 
which  the  exact  ratio  is  preserved,  and  the  idea  of  a  fraction  of  an 
atom  avoided. 

If  the  atoms  occupied  the  same  space  when  in  a  gaseous  form,  they 
might  be  represented  by  volumes,  and  their  proportional  numbers 
would  be  identical  with  their  specific  gravities.  This,  however,  is 
not  the  case.  The  atom  of  hydrogen,  and  several  other  gaseous  sub- 
stances occupy  twice  the  space  of  an  atom  of  oxygen ;  but  in  such 
cases  it  is  easy  to  calculate  the  specific  gravity  by  multiplying  the 
atomic  weight  by  half  the  specific  gravity  of  oxygen. 

It  might  at  first  view  appear  that  the  atoms  and  volumes  could  be 
made  to  correspond,  if  we  considered  water  as  a  compound  of  two 
atoms  of  hydrogen  and  one  atom  of  oxygen.  This  has  been  propos- 
ed by  Sir  H.  Davy,  and  advocated  by  other  chemists  ;  but  it  increas- 
es instead  of  removing  the  difficulty.  Thus  sulphuretted  hydrogen, 
on  this  supposition,  must  be  considered  as  consisting  of  one  atom  of 
sulphur  and  two  atoms  of  hydrogen,  while  it  is  composed  of  one 
volume  of  each  of  the  constituents.  Muriatic  acid  gas  would  be  one 
atom  of  chlorine  and  two  atoms  of  hydrogen,  though  constituted  in 
like  manner  of  one  volume  of  each  gas.  And  the  same  remark 
would  be  applicable  to  hydriodic  acid,  hydrocyanic  acid,  and  indeed 
to  most  other  compound  gases  containing  hydrogen.  For  this  and 
other  reasons  which  might  be  given,  water  is  considered  a  compound 

*  These  terms  have  been  proposed  to  avoid  theoretical  annunciations; 
but  the  term  atom  originally  proposed  by  Mr.  Dalton  is  generally  employed 
ia  this  work  as  being  the  most  convenient.  And  1  thin!;  Dr.  Thomson  has  cor- 
rectly remarked  that  "  unless  we  adopt  the  hypothesis  with  which  Da! ton  set 
out,  namely  that  the  ultimate  particles  of  bodies  are  atoms  incapable  of  far- 
ther division,  and  that  chemical  combination  consists  in  the  union  of  these  atoms 
\vith  each  other,  we  lose  all  the  new  light  which  the  atomic  theory  throws 
upon  chemistry,  and  bring  our  notions  back  to  the  obscurity  of  the  days  of 
J3er£mau  and  Bertho!let." — History  of  Chemistry. 


34  HEAT  OR   CALORIC. 

of  one  atom  of  hydrogen  and  one  atom  of  oxygen,  though  the  vol- 
ume of  oxygen  is  only  one  half  that  of  the  hydrogen*. 

The  learner  will  now  see  the  reason  why  the  atomic  weight  of  oxy- 
gen is  fixed  at  8  compared  to  hydrogen  1,  although  its  specific  grav- 
ity is  16  when  compared  to  the  same  substance  as  unity. 

Laws  of  Berzelius. 

The  peculiar  views  of  this  celebrated  chemist,  are  stated  in  an  8vo. 
volume  entitled,  Essai  sur  la  Theorie  des  Proportions  Chimiques.  Paris , 
1819  ;  and  also  in  the  article  Proportions,  Determinate ,  of  Dr.  Brews- 
ter's  Edinburgh  Encyclopaedia.  The  facts  contributed  by  this  cele- 
brated chemist,  in  proof  of  the  laws  of  definite  and  multiple  propor- 
tions, are  of  the  highest  importance.  But  in  deducing  general  laws 
he  does  not  appear  to  have  been  equally  fortunate.  At  least  they 
have  not  gained  much  sanction.  It  is  to  be  regretted,  moreover,  that 
his  nomenclature  is  shrouded  in  language  and  symbols  calculated  to 
confuse  and  perplex  the  learner.  Though  I  shall  constantly  avail 
myself  of  the  experimental  investigations  of  this  able  chemist,  I 
shall  be  content  with  referring  those  who  wish  to  study  his  general 
theories  to  the  works  above  quoted,  and  to  Turner's  Chemistry,  2d 
edition.  Berzelius'  Table  of  Atomic  Weights,  and  the  explanation  of 
his  symbols,  are  also  contained  in  the  appendix  to  the  2d  volume  of 
Henry's  Chemistry. 

REFERENCES. — Turner's  Chemistry.  Urejs  Cheat.  Dictionary,  Art.  Equi- 
valent. Professor  Olmstead  on  the  present  state  of  Chemical  Science. — 
Sillimart's  Jour.  xii.  1 ;  a  paper  containing  a  very  lucid  explanation  of  the 
Laws  of  Combination  and  of  the  Atomic  Theory,  from  which  some  of  the 
ideas  in.  the  above  section  are  obtained.  McNevin  on  the  Atomic  Theory. 
Thomson's  Fi-st  Principles,  v,  1.  Dalton's  neio  system  of  Chemical  Philo- 
sophy, v.  1.  Berthollefs  Chemical  statistics.  Some  interesting  papers  con- 
cerning the  Atomic  Theory,  by  Berzelius,  Dalton  and  Thorn-son,  will  be 
found  in  the  %d,  3d,  4th  and  5lh  volumes  of  the  Annals  of  Philosophy.  J9a- 
vy's  Element's  of  Chem.  Phil.  Thenard's  Traite  de  Chim.  5th  eel.  v.  1  and 
5.  Prout  on  the  relations  between  the  specific  gravity  of  Gaseous  Bodies,  and 
the  weights  of  their  Atoms. — Ann.  of  Phil.  vi.  321.  vii.  111.  Thomson  and 
Gay  Lussac  on  the  same  subject — same  work,  vii.  343.  ix.  15.  Murray  on  the 
relation  of  the  Law  of  Definite  Propositions  in  Chemical  Combination,  to 
the  constitution  of  Acids,  Alkalies  and  Earths. — Ann.  of  Phil.  xiv.  281.  344.. 
Daubeny  on  the  Atomic  Theory. 


CHAPTER  II. 

HEAT    OR    CALORIC. 

The  term  Heat,  in  common  language,  has  two  meanings :  in  the 
one  case  it  implies  the  sensation  experienced  on  touching  a  hot  body  ; 
in  the  other,  it  expresses  the  cause  of  that  sensation.  To  avoid  any 
ambiguity  that  may  arise  from  the  use  of  the  same  expression  in  two 
such  different  senses,  the  word  caloric  (from  the  latin  color,  heat)  has 
been  adopted  to  designate  exclusively  the  principle  or  cause  of  the 

*  Mr.  Finch  in  his  paper  on  the  Atomic  theory,  ( Silliman's  Jour.  xiv.  24.) 
has  evidently  overlooked  all  these  difficulties. 


NATURE   OF    CALORIC.  35 

feeling  of  heat ;  but  to  prevent  repetition,  the  terms  caloric  and  heat 
are  both  occasionally  employed  to  designate  the  cause  in  question. 
This  subject  will  be  treated  of  in  the  following  order  : 

1.  THE  NATURE  OF  CALORIC. 

2.  ITS  COMMUNICATION. 

3.  ITS  DISTRIBUTION. 

4.  ITS  EFFECTS. 

5.  SPECIFIC  CALORIC. 

6.  THE  SOWRCES  OF  CALORIC. 

SECTION  I. 

NATURE    OP    CALORIC. 

Upon  this  point  philosophers  are  divided  into  two  sets  ;  the  one 
maintaining  that  caloric  is  a  mere  property  of  matter  ;  the  other  that 
it  is  a  distinct  substance.  The  former  is  an  old  opinion,  but  was 
adopted  by  Sir  H.  Davy,  and  is  at  the  present  time  quite  generally 
received  in  France.  The  latter  was  maintained  by  Sir  Isaac  New- 
ton ;  and  as  this  affords  a  more  easy  explanation  of  most  of  the 
chemical  phenomena,  it  will  be  adopted  in  the  present  treatise. 

Caloric,  on  the  supposition  of  its  being  material,  is  a  subtle  fluid, 
the  particles  of  which  repel  one  another,  and  are  attracted  by  all  other 
substances.  It  is  imponderable  ;  that  is,  it  is  so  exceedingly  light  that 
a  body  undergoes  no  appreciable  change  of  weight,  either  by  the  ad- 
dition or  abstraction  of  caloric.  It  is  present  in  all  bodies,  and  can 
not  be  wholly  separated  from  them.  For  if  we  take  any  substance 
whatever,  at  any  temperature,  however  low,  and  transfer  it  into  an 
atmosphere,  whose  temperature  is  still  lower,  a  thermometer  will  in- 
dicate that  caloric  is  escaping  from  it.  That  its  particles  repel  one 
another,  is  proved  by  observing  that  it  flies  off  from  a  heated  body  ; 
and  that  it  is  attracted  by  other  substances,  is  equally  manifest  from 
the  tendency  it  has  to  penetrate  their  particles  and  be  retained  by 
them.  —  Turner. 

Caloric  has  also  been  defined  as  the  agent  to  which  the  phenomena  of 
heat  and  combustion  are  to  be  ascribed.  So  far  as  chemical  agencies 
are  concerned  it  is,  1st.  An  antagonist  power  to  cohesive  attraction  ; 
and,  2d.  It  concurs  with,  and  increases  elasticity. 

Caloric,  in  many  of  its  properties,  resembles  light.  As  for  example, 
in  those  of  refraction,  reflection  and  radiation,  and  in  the  repulsion 
which  exists  between  its  particles.  This  latter  property  indeed,  is  so 
striking  that  caloric  is  often  treated  of  under  the  appellation  of  calorific 
repulsion. 

As  the  presence  of  caloric  produces  the  sensation  of  heat,  so  its  ab- 
sence produces  that  of  cold.  This  last  sensation,  therefore,  is  not  to 
be  considered  as  produced  by  any  particular  agent,  but  as  altogether 
a  negative  expression. 

Caloric  exists  in  two  states  viz  :  free  or  sensible,  and,  latent  or  corn- 
lined. 

In  the  former  state  it  is  capable  of  exciting  the  sensation  of  heat, 
and  of  producing  expansion  in  other  bodies,  and  to  it  the  term  caloric 
of  temperature  has  also  been  applied.  By  the  term  temperature,  we 
are  to  understand  the  state  of  a  body  relatively  to  its  power  of  excit- 
ing the  sensation  of  heat,  and  occasioning  expansion  ;  effects,  which 
in  all  probability,  bear  a  proportion  to  the  quantity  of  free  caloric  in  a 


36  COMMUNICATION   OF   CALORIC. 

given  space,  or  in  a  given  quantity  of  matter.  Thus  what  we  call  a 
high  temperature  may  be  ascribed  to  the  presence  of  a  large  quantity 
of  free  caloric;  and  a  low  temperature  to  that  of  a  small  quantity. 
We  are  unacquainted,  however,  with  the  extremes  of  temperature  ; 
and  may  compare  it  to  a  chain,  of  which  a  few  of  the  middle  links 
only  are  exposed  to  our  observation,  while  its  extremities  are  far  re- 
moved from  our  view. — Henry's  Chem.  i.  82. 

In  the  latter  state,  caloric  exists  either  in  combination  with  bodies 
or  in  something  resembling  it.  Under  these  circumstances,  it  does 
not  possess  its  distinguishing  properties — cannot  be  discovered  by  our 
senses  or  by  the  thermometer,  and  produces  important  and  sometimes 
permanent  changes  in  the  bodies  with  which  it  combines.  The  dif- 
ference between  these  two  states  may  be  shown  by  the  following  ex- 
periment : 

Exp.  Place  two  vessels  of  thin  glass,  the  one  containing  water  and 
the  other  a  small  portion  of  sulphuric  acid,  in  contact  with  the  bulb 
of  an  air  thermometer.  Allow  them  to  remain  in  this  situation  for  a 
short  time,  to  show  that  the  thermometer  is  not  affected  by  them. 
Now  empty  the  sulphuric  acid  into  the  water,  when  it  will  be  seen 
that  the  liquid  in  the  thermometer  descends,  owing  to  the  expansion 
of  the  air  by  the  caloric  which  has  been  rendered  free  by  the  mixture. 
The  common  fire  syringe  offers  another  striking  illustration  of  the 
difference  between  combined  and  free  caloric. 

REFERENCES. — For  a  notice  of  facts  and  reasonings  concerning  the  nature 
of  Caloric,  see  Thomson's  Chemistry,  vol.  1  /  and  Library  of  Useful  Know- 
ledge, Art.  Heat.  Professor  Hare's  paper,  on  the  materiality  of  Heat,  and. 
the  discussion  on  this  subject  between  him  and  Prof.  Olmslead. — Sillimaifs 
Amer.  Jour.  vols.  iv.  xi.  xii.  xiii. 

SECTION  II. 

COMMUNICATION    OF    CALORIC. 

Caloric  is  radiated  in  all  directions,  and  moves  with  great  velocity. 
It  is  also  absorbed  by  certain  bodies,  and  when  it  has  thus  entered,  it 
makes  its  way  through  the  body.  In  the  latter  case  its  motion  is 
comparatively  slow.  Hence  caloric  is  communicated, 

1.  BY  RADIATION. 

2.  BY  CONDUCTION. 

KADIATION. 

When  the  hand  is  placed  above  a  heated  ball,  or  a  fire,  the  sensa- 
tion of  heat  is  perceived  ;  and  the  same  thing  also  takes  place  when 
the  hand  is  placed  below  the  source  of  caloric.  Now  as  nothing  in- 
tervenes in  the  last  case  but  the  air,  and  as  this  fluid,  when  caloric  is 
communicated  to  it  expands  arid  rises,  the  impression  cannot  be 
owing  to  the  transmission  of  hot  air  to  the  hand  ;  but  rather  to  the 
action  of  the  particles  of  caloric  which  are  supposed  to  be  thrown  off 
in  all  directions.  Bodies  capable  of  discharging  caloric  in  this  way 
are  called  Radiating  ;  and  the  principle  which  is  thus  projected,  Radi- 
ant Caloric. 

Radiant  Caloric  is  reflected. 

This  fact  can  be  shown  in  a  familiar  manner,  by  standing  at  the  side 
of  a  fire  in  such  a  position  that  the  caloric  cannot  reach  the  face  di- 


COMMUNICATION   OF   CALORIC.  37 

rectly,  and  then  placing  a  plate  of  tinned  iron  opposite  the  grate  and 
at  such  an  inclination  as  permits  the  observer  to  see  in  it  the  reflection 
of  the  fire ;  as  soon  as  it  is  brought  to  this  inclination,  a  distinct  im 
pression  of  heat  will  be  perceived  upon  the  fa'ce.  If  a  line  be  drawn 
from  the  heated  substance  to  the  point  of  a  plane  surface  from  which 
it  is  reflected,  and  a  second  line  from  that  point  to  the  spot  where  it 
produces  its  effect,  the  angles  which  these  lines  form  with  a  line  per- 
pendicular to  the  reflecting  plane  are  equal  to  each  other,  or  in  phi- 
losophical language,  the  angle  of  incidence  is  equal  to  the  angle  of  re- 
,  flexion. — Turner. 

This  may  be  illustrated  in  a  still  more  striking  manner,  by  the  ex- 
periment devised  by  Pictet,  which  is,  to  take  two  concave  mirrors  of 
planished  tin  or  copper,  and  to  place  them  at  a  distance  of  from  9  to  12 
feet  apart,  with  their  concave  surfaces  towards  each  other.  If  now  a 
hot  ball  or  a  small  basket  of  coals  is  placed  in  the  focus  of  one  mirror, 
it  will  instantly  affect  a  thermometer  in  the  focus  of  the  other  ;  or  if  a 
piece  of  phosphorus  be  substituted  for  the  thermometer,  it  will  soon  be 
kindled. 

Now  these  phenomena  cannot  be  explained  upon  the  supposition 
that  the  heat  of  the  ball  or  of  the  coals  is  communicated  directly  to 
the  thermometer  through  the  medium  of  the  air  which  intervenes ; 
for  upon  this  hypothesis,  a  point  intermediate  between  the  two  mir- 
rors would  be  of  a  higher  temperature  than  that  directly  in  the  focus, 
which  is  not  the  case.  There  must,  therefore  be  something  emanating 
from  the  ball  or  the  coals  which  is  reflected  by  the  mirrors,  and  is  con- 
centrated also  into  a  focus,  so  as  to  affect  the  thermometer  and  the 
phosphorus. 

When  the  heated  ball  is  placed  near  the  mirror,  rays  of  heat  fly  off 
from  it  in  straight  lines  to  the  mirror,  by  which  they  are  instantly  re- 
flected again  In  straight  lines  to  the  opposite  one,  where  they  are  also 
reflected,  and  are  thus  brought  to  a  point  where  the  heating  effect  is 
produced.  The  distance  at  which  this  takes  place,  depends  of  course 
on  the  form  of  the  mirror  ;  and  the  effect  is  much  greater  when  burn- 
ing charcoal  is  employed  instead  of  the  heated  ball.  But  the  thermo- 
meter is  affected  even  when  a  glass  of  boiling  water  is  substituted  for 
the  heated  ball. 

Radiant  Caloric  is  absorbed. 

This  may  be  shown  by  placing  a  thermometer  before  the  fire  or  any 
heated  body,  when  the  mercury  will  be  seen  to  rise  in  the  stem.  And 
it  has  been  ascertained  that  the  intensity  of  effect  diminishes  according 
to  the  squares  of  the  distance  from  the  radiating  point.  Thus  the 
thermometer  will  indicate  four  times  less  heat  at  two  inches,  nine  times 
less  at  three  inches,  and  sixteen  times  at  four  inches,  than  it  did  when 
it  was  only  one  inch  from  the  heated  substance. 

It  is  therefore  evident  that  a  hot  body  placed  in  the  air  is  the  centre 
of  a  multitude  of  calorific  rays  ;  that  these  rays  traverse  the  air  almost 
without  resistance  ;  and  that  when  they  fall  upon  the  surface  of  a  sol- 
id or  liquid  substance  they  are  either  reflected  from  it  and  receive  a 
new  direction,  or  lose  their  radiant  form  altogether,  and  are  absorbed. 
With  regard  to  caloric  then,  three  powers  may  be  recognized  as  belonging 
to  bodies,  viz.  1.  The  power  of  emitting  or  radiating  caloric  ;  2.  Tha 
power  of  absorbing  ;  and  3.  The  power  of  reflecting  caloric.  These 
powers  appear  to  depend  chiefly  upon  the  temperature,  and  polish  upon 
the  surface  of  the  body :  their  nature  having  but  little  influence. 

Temperature.     The  higher  a  body  is  heated,  the  greater  is  its  radia- 


38  COMMUNICATION    OF   CALORIC- 

ting  power;   for  then  the  caloric  of  the  body  has  greater  tension,  or  in 
other  words,  makes  more  effect  to  escape. 

Polish  of  surface.  When  even  a  large  quantity  of  radiant  caloric 
falls  upon  a  metallic  body  highly  polished,  the  body  is  scarcely  heat- 
ed ;  from  which  we  infer  that  all  the  caloric  has  been  reflected.  But 
if  we  blacken  the  surface  of  this  body  and  expose  it  again  to  the  same 
amount  of  caloric,  it  becomes  considerably  heated ;  and  in  this  case 
nearly  all  the  caloric  will  be  absorbed. 

Polish  influences  the  radiating,  as  well  as  the  absorbing  and  reflect- 
ing power.  This  is  strikingly  illustrated  by  the  experiment  of  Mr, 
Leslie.  He  coated  one  side  of  a  canister  with  lampblack,  covered  a 
second  with  writing  paper,  applied  to  a  third  a  pane  of  glass,  and  left 
the  fourth  bright  and  polished.  The  canister  was  now  filled  with 
boiling  water  and  placed  in  the  focus  of  the  mirror.  When  the  me- 
tallic surface  was  presented  to  the  reflector,  the  impression  upon  the 
thermometer  amounted  to  12Z  ;  from  the  glass  surface  it  was  equal  to 
90°  ;  from  the  papered  side  98°  ;  and  100°  from  the  lampblack. 

The  powers  of  bodies  to  radiate  and  absorb  caloric  are  directly 
proportional  to  each  other.  Those  which  absorb  with  the  most  ease 
also  radiate  with  the  greatest  facility.  If  in  the  usual  arrangement, 
the  bulb  of  the  thermometer  be  coated  with  tin  foil,  or  even  gold 
leaf,  the  impression  of  the  radiant  caloric  will  be  exceedingly  slight ; 
if  the  bulb  be  naked,  the  effect  will  be  much  greater,  but  if  it  be  coat- 
ed with  lampblack,  the  action  on  the  instrument  will  reach  its  maxi- 
mum. Now  experiments  have  proved  that  lampblack  absorbs  more 
than  glass,  and  glass  more  than  the  metals,  which  is  exactly  the  order 
of  their  radiating  powers. — Leslie's  Inquiry. 

The  powers  of  radiation  and  reflection  are  inversely  proportional  to 
each  other.  Those  bodies  which  reflect  the  most,  radiate  the  least, 
and  those  which  radiate  the  most,  reflect  the  least  caloric.  Thus 
metals  reflect  heat  with  great  facility  ;  but  if  a  glass  mirror  be  substi- 
tuted for  the  metallic  reflector,  the  positions  of  the  hot  body  and  the 
thermometer  being  the  same,  the  effect  will  be  considerably  diminish- 
ed, and  if  the  surface  of  the  glass  be  coated  with  lampblack,  no  action 
upon  the  thermometer  will  be  perceived. 

The  vast  superiority  of  metallic  bodies  over  glass  in  reflecting  ca- 
loric may  be  proved  by  a  very  simple  experiment.  In  the  focus  of 
the  commonest  tin  reflector,  if  at  all  approaching  to  a  concave  or 
parabolic  form,  when  held  before  a  large  fire,  a  considerable  degree 
of  warmth  will  be  perceived ;  whereas  the  best  glass  mirror  of  the 
same  dimensions  will  hardly  collect  in  its  focus  heat  enough  to  be  felt. 

On  the  other  hand,  glass  radiates  more  caloric  than  the  metals,  and 
lampblack  more  than  glass.  If  the  surface  of  the  metallic  mirror  be 
furrowed  or  roughened,  or  if  it  be  covered  with  a  thick  film  of  amal- 
gam, its  powers  to  reflect  caloric  will  be  diminished,  while  the  power 
to  radiate  will  be  proportionably  increased.  Metallic  bodies  possess 
this  property  in  different  degrees,  and  it  will  be  seen,  by  inspecting 
the  table  of  Mr.  Leslie,  that  those  which  reflect  the  most,  radiate  the 
least,  and  that  the  converse  of  the  proposition  is  equally  true.  It  also 
appears  as  might  be  expected,  that  the  reflecting  and  absorbing  pow- 
ers of  bodies  are  in  the  inverse  ratio  to  each  other. 

In  ordinary  cases  heat  is  radiated  through  the  medium  of  the  air  ; 
and  no  sensible  radiatiton  takes  place  when  the  whole  apparatus  is 
plunged  into  water — although  the  experiments  on  this  point  are  not 
free  from  objection.  It  radiates  through  all  gaseous  bodies  tried,  and 
it  does  not  appear  that  the  rate  of  radiation  is  much  influenced  by  the 


COMMUNICATION    OF   CALORIC.  39 

surrounding  medium.  The  rate  is  the  same  at  least,  in  air,  and  in 
hydrogen  gas  ;  and  oxygen  and  nitrogen  appear  to  have  the  same  pro- 
perties in  this  respect  as  air.  Mr.  Leslie  has  shown  also  that  the  rari- 
fication  of  the  surrounding  air  diminishes  somewhat  the  radiating  en- 
ergy of  surfaces  ;  but  the  radiation  diminishes  at  different  rates  in  dif- 
ferent gases.  He  has  given  a  table  showing  the  diminution  of  the 
power  of  radiation  in  air  and  in  hydrogen  gas  of  different  degrees  of  rari- 
ty ;  but  perhaps  the  experiments  require  to  be  repeated. 

It  has  bsen  supposed  that  solid  bodies  are  impermeable  to  radiant 
caloric,  and  an  experiment  is  described  in  some  chemical  works  as 
a  conclusive  proof  of  the  difference  between  caloric  and  light.  It 
consists  in  placing  a  lamp  or  burning  coals  in  the  focus  of  a  mirror, 
and  a  pane  of  glass  between  it  and  the  opposite  mirror  :  the  rays  of 
light  will  pass  through  the  glass,  but  the  rays  of  caloric,  it  is  said, 
will  be  completely  intercepted.  But  this  distinction  can  scarcely  be 
maintained.  It  is  true  indeed  that  the  thermometer  is  not  BO  much 
affected  as  it  would  be  were  no  screen  interposed,  and  the  glass  itself 
becomes  warm.  These  facts  prove  that  the  greater  part  of  the  calori- 
fic rays  is  intercepted  by  the  glass.  But  the  thermometer  is  affected 
to  a  certain  degree,  and  the  question  is,  by  what  means  do  the  rays 
reach  it  1  Professor  Leslie  contends,  that  all  the  rays  which  fall  upon 
the  glass  are  absorbed  by  it,  pass  through  its  substance  by  its  con- 
ducting power,  and  are  then  radiated  from  the  other  side  of  the  glass 
towards  the  thermometer — an  opinion,  which  Dr.  Brewster  has  ably 
supported  with  an  argument,  suggested  by  his  optical  researches. — 
[Phil.  Trans,  for  1816,  p.  106.]  The  experiments  of  Delaroche,  on 
the  contrary,  [Biot.  Traite  de  Phys.]  lead  to  the  conclusion  that  glass 
does  transmit  some  calorific  rays,  the  number  of  which,  in  relation  to 
the  quantity  absorbed,  is  greater  as  the  intensity  of  the  heat  increas- 
es. This  general  result  has  been  confirmed  by  various  other  philoso- 
phers. 

Mr.  Leslie  has  advanced  the  idea  that  radiant  caloric  is  not  thrown 
off  from  hot  bodies  and  darted  through  the  air  to  distant  bodies,  but 
that  the  air  itself  is  the  medium  of  its  transmission.  According  to 
this  hypothesis,  the  stratum  of  air  immediately  in  contact  with  the 
heated  body  acquires  a  portion  of  its  high  temperature,  by  which  it 
is  expanded  and  made  to  press  upon  the  next  stratum  of  particles  ; 
this  in  like  manner  recedes,  and  thus  an  undulation  or  chain  of  serial 
pulsations  is  produced.  "The  mass  of  air,  without  sensibly  chang- 
ing its  place,  suffers  only  a  slight  fluctuation  as  it  successively  feels 
the  partial  swell ;  but  the  heat  attached  to  this  state  of  dilatation  is 
actually  transported,  and  with  the  swiftness  of  sound." — Leslie's  In- 
quiry, p.  140. 

But  the  experiments  of  Delaroche  and  others,  offer  insuperable 
objections  to  the  adoption  of  Leslie's  theory,  and  indeed  go  to  prove 
that  there  is  but  little  difference  between  the  radiation  of  heat  and 
light. 

When  a  cold  body,  as  ice  or  a  vessel  containing  a  mixture  of  snow 
and  salt,  is  placed  in  the  focus  of  one  of  the  mirrors,  instead  of  the 
hot  body,  the  bulb  of  the  thermometer  in  the  focus  of  the  other  mir- 
ror will  indicate  a  diminution  of  temperature  below  that  of  the  sur- 
rounding air.  This  fact  led  some  philosophers  to  advance  the  opin- 
ion that  cold  was  a  material  substance,  and  subject,  like  heat,  to  the 
laws  of  radiation  and  reflection.  But  this,  as  well  as  the  other  phe- 
nomena of  radiant  caloric,  will  be  explained  in  the  section  on  the  dis- 
tribution of  temperature.  It  should  be  observed,  that  in  all  these  ex- 


40  COMMUNICATION   OF  CALORIC. 

periments  upon  the  radiation  of  caloric,  the  Differential .  Thermometer, 
described  in  Section  4,  should  be  employed. 

RKFERENCKS.  Leslie's  Inquiry.  PicteCs  Essay.  Delaroclie  on  Radi- 
ant Heat— -Ann.  of  Phil.  ii.  100.  Ritche  in  Edin.  Phil.  Jour.  xi.  281. 
Prof.  Powell  in  Repertory  of  Inventions,  iv.  394 — Also  Ami.  of  Phil,  xxiv, 
xxv,  and  TL\\\.—Pou:elPs  Report  on  Radiant  Heat  to  the  British  Associa- 
tion, 1832. 

CONDUCTION. 

Another  method  in  which  heat  is  communicated,  is  by  what  has 
been  aptly  termed  conduction,  which  differs  considerably  from  radia- 
tion. The  most  striking  point  of  difference,  however,  is  the  veloci- 
ty with  which  caloric  is  transmitted.  When  caloric  is  radiated,  its  mo- 
tion is  rapid,  nay  almost  instantaneous  ; — when  it  is  conducted,  its 
motion  is  slow.  These  two  modes  of  communication,  however,  are 
seldom  perfectly  independent  of  each  other.  When  caloric  is  radia- 
ted through  the  air,  a  portion  is  also  conducted  by  the  air  which 
comes  in  contact  with  the  rays.  And  again,  when  caloric  is  conduct- 
ed through  a  solid  body,  for  example,  radiation  at  the  same  time  takes 
place.  The  difference  in  the  velocity  of  transmission  will  explain 
why,  in  the  former  case,  only  a  small  portion  of  heat  is  conducted, 
and  in  the  latter  case  why  so  large  a  quantity  is  radiated. 

Caloric  is  conducted  through  solids,  liquids  and  triform  substan- 
ces ;  in  each  of  these  bodies,  however,  there  is  some  peculiarity  in 
the  manner  of  its  conduction. 

Conducting  powers  of  Solids. 

When  a  metallic  bar,  iron  for  example,  is  exposed  at  one  end  to  the  heat 
of  a  furnace,  the  heat  is  gradually  transmitted  through  its  whole  length, 
and  after  a  short  time  the  other  extremity  cannot  be  touched  without 
danger  of  our  being  burnt.  But  this  may  be  done  with  perfect  safety 
with  a  rod  of  glass  or  of  wood.  Hence  bodies  are  said  to  differ  in  their 
power  of  conducting  caloric,  and  some  are  called  good  and  others  bad 
conductors. 

Metals  are  the  best  conductors  of  caloric ; — but  even  among  these 
there  is  considerable  difference.  According  to  the  experiments  of  In- 
genhouz,  silver  and  gold  are  the  best  conductors,  next  copper  and  tin, 
which  are  nearly  equal,  and  lastly  platinum,  iron,  and  lead,  which  are 
much  inferior  to  the  others. 

Glass,  pottery,  clay,  &c.  have  much  less  conducting  power  than 
any  of  the  metals.  This  is  the  reason  why  glass  is  so  liable  to  break 
when  suddenly  heated  or  cooled  ;  one  part  of  it  is  receiving  or  part- 
ing with  its  caloric  before  the  rest  expands  or  contracts,  and  hence 
the  cohesion  is  destroyed.  It  is  on  this  account  that  the  manufac- 
turers resort  to  a  process  called  annealing,  which  consists  in  putting 
the  glass  while  hot,  immediately  after  being  formed  into  the  required 
shape,  into  an  oven  strongly  heated,  where  the  glass  remains  till  it 
becomes  cold  by  slow  degrees. 

Exp.  Put  a  lamp  under  the  centre  of  a  sheet  of  copper,  and  at  equal 
distances  from  the  centre  place  a  piece  of  silver,  copper,  iron  and  por- 
celain, of  the  same  size  and  thickness,  having  on  each  a  small  bit  of 
phosphorus.  That  on  the  silver  will  be  first  kindled,  showing  that  it  is 
soonest  heated  ;  in  other  words,  that  the  caloric  has  passed  most  quick- 
ly through  it.  Next  comes  the  copper,  then  the  iron,  and  lastly  the 
porcelain,  the  phosphorus  on  which  will  remain  a  long  time,  without 
being  kindled. 


COMMUNICATION   OF   CALORIC.  41 

Next  to  these  bodies  in  point  of  conducting  power,  come  the  dried 
woods,  which  also  differ  materially  from  each  other.  According  to 
Professor  Mayer,  the  conducting  power  of  these  is  inversely  as  their 
specific  gravities.  (See  his  table  in  Webster's  Brande.) 

The  difference  between  the  conducting  power  of  the  metals  and 
wood  may  be  shown  as  follows  : 

Exp.  Take  a  smooth  cylindrical  tube,  or  still  better,  a  solid  piece 
of  metal,  about  an  inch  and  a  half  in  diameter  and  eight  inches  long ; 
wrap  a  clean  piece  of  writing  paper  round  the  metal  so  as  to  be  in 
close  contact  with  its  surface.  When  thus  prepared  it  may  be  held 
for  a  considerable  time  in  the  flame  of  a  spirit  lamp  without  being  in 
the  least  affected.  Wrap  a  similar  piece  of  paper  around  a  cylindrical 
piece  of  wood  of  the  same  diameter,  and  hold  it  in  the  flame  ;  it  will 
speedily  burn.  When  the  paper  is  in  close  contact  with  the  metal, 
the  heat  which  is  applied  to  it  in  one  particular  part  cannot  accumu- 
late there,  but  enters  into  the]  metal,  and  is  equally  diffused  through 
its  substance,  so  that  the  paper  cannot  be  burned  or  scorched,  until 
the  metal  becomes  very  hot :  but  when  the  paper  is  wrapped  round 
wood,  the  heat  that  is  applied  in  one  particular  part,  not  being  able  to 
enter  into  the  wood  with  facility,  accumulates  in  a  short  time  in  suffi- 
cient quantity  to  burn  the  paper. — L.  U.  K.  Art.  Heat. 

Charcoal  is  also  a  bad  conductor  :  but  feathers,  silk,  wool  and  hair 
are  worse  than  any  yet  mentioned.  Count  Rumford  has  made  ex- 
periments with  a  view  of  determining  the  conducting  power  of  sub- 
stances of  this  nature,  from  which  it  appears  that  those  have  the  least 
conducting  power,  in  which  tfce  fibres  are  finest  and  most  condensed, 
provided  the  interstitial  air  is  not  expelled  by  the  condensation. — Rum- 
ford's  Essays. 

The  substances  which  form  the  warmest  articles  of  clothing  are 
those  which  have  the  longest  nap,  fur  or  down,  on  account  of  the 
air  which  is  involved,  resisting  the  escape  of  the  natural  warmth  of 
the  body.  The  imperfect  conducting  power  of  snow  arises  from  the 
same  cause,  and  hence  its  utility  in  preventing  the  surface  of  the 
earth  from  being  injuriously  cooled  in  many  parts  of  the  world. 
While  the  temperature  of  the  air  in  Siberia  has  been — 70D  F.  it  is 
affirmed  that  the  surface  of  the  earth  has  seldom  been  colder  than 
32-  F. 

Despretz  has  given  the  following  table  of  the  comparative  conduct- 
ing powers  of  the  principal  metals  and  some  earthy  bodies. — Ann.  de 
Chim.  et  de  Pk.  xxxvi.  422. 

Gold,  (greatest  conducting  power,)        1000.0 

Platinum, 981.0 

Silver,      ......          973.0 

Copper,   -        -        -        -  898.2 

Iron,         -        -        -        -        -        -          374.3 

Zinc, 363.0 

Tin, 303.9 

Lead, 179.6 

Marble, 23.6 

Porcelain, 32.2 

Earth  of  bricks  and  furnaces,  -         -  11.4 

The  conducting  powers  of  bodies  have  been  investigated  by  Fourier, 
by  the  aid  of  instruments  called  a  Thermometer  of  Contact,  and  a  Ther- 


42  COMMUNICATION    OF    CALORIC. 

moscope  of  Contact,  from  the  first  of  which  some  curious  facts  have 
been  ascertained. — See  Henry's  Chem.  i.  108.  Ann.  de  Ctitm.  et  dt 
Ph.  xxxvii.  291. 

Conducting  powers  of  Liquids. 

Liquids  may  be  said,  in  one  sense  of  the  word,  to  have  the  power 
of  communicating  caloric  with  great  rapidity,  and  yet  they  are  very 
imperfect  conductors.  The  transmission  of  caloric  from  particle  to 
particle  does  in  reality  take  place  very  slowly  ;  but  in  consequence  of 
the  mobility  of  their  particles  upon  each  other,  there  are  peculiar  in- 
ternal movements  which  under  certain  circumstances  may  be  occa- 
sioned in  them  by  increase  of  temperature,  and  which  do  more  than 
compensate  for  the  imperfect  conducting  power  with  which  they  are 
really  endowed. 

"When  certain  particles  of  a  liquid  are  heated,  they  expand,  and  thus 
become  specifically  lighter  than  those  which  have  not  yet  received  an 
increase  of  temperature ;  and  consequently,  according  to  a  well- 
known  law  in  physics,  the  colder  and  denser  particles  descend,  while 
the  warmer  ones  are  pressed  upwards.  It  therefore  follows  that  if 
caloric  enter  at  the  bottom  of  a  vessel  containing  any  liquid,  a  double 
set  of  currents  must  be  immediately  established,  the  one  of  hot  parti- 
cles rising  towards  the  surface,  and  the  other  of  colder  particles  des- 
cending to  the  bottom.  Now  these  currents  take  place  with  such  ra- 
pidity, that  if  a  thermometer  be  placed  at  the  bottom,  and  another  at 
the  top  of  a  long  jar,  the  fire  being  applied  below,  the  upper  one  will 
begin  to  rise  almost  as  soon  as  the  lower.  Hence,  under  certain  cir- 
cumstances, caloric  is  rapidly  communicated  through  liquids. 

But  if,  instead  of  heating  the  bottom  of  the  jar,  the  caloric  is  made 
to  enter  by  the  upper  surface,  very  different  phenomena  will  be  ob- 
served. The  intestine  movements  cannot  now  be  formed,  because  the 
heated  particles  have  a  tendency  to  remain  constantly  at  the  top  ;  the 
caloric  can  descend  through  the  fluid  only  by  transmission  from  parti- 
cle to  particle,  a  process  which  takes  place  so  very  tardily,  as  to  have 
induced  Count  Rumford  to  deny  that  water  can  conduct  at  all,  and 
to  assert  that  liquids  were  heated  exclusively  by  their  transporting  or 
carrying  power. — (Rumford's  Essays.)  The  incorrectness  of  this 
opinion,  however,  appears  to  be  quite  satisfactorily  shown  by  the  ex- 
periments of  Dr.  Hope,  Dr.  Thomson  and  Dr.  Murray ;  though  they 
all  admit  that  water,  and  liquids  in  general,  mercury  excepted,  possess 
the  power  of  conducting  caloric  in  a  very  slight  degree.* 

The  transporting  power  of  liquids  can  be  very  satisfactorily  shown 
by  putting  into  a  vessel  of  water  some  small  pieces  of  amber  which 
are  in  specific  gravity  so  nearly  equal  to  water  as  to  be  little  influenced 
by  gravitation. 

The  lowermost  part  of  the  vessel  being  subjected  to  heat,  when 
thus  prepared,  the  pieces  of  amber  rise  vertically,  and  on  reaching  the 
surface,  move  towards  the  sides  of  the  vessel,  which  are  colder  from 
the  influence  of  the  external  air  ;  they  then  sink  and  rise  again  as  be- 
fore. 

When  the  boiling  point  is  nearly  attained,  the  particles  being  nearly 
of  one  temperature,  the  circulation  is  retarded.  The  portions  on  the 
surface  are  converted  into  steam  before  they  can  be  succeeded  by 
others  ;  but  the  steam  thus  produced  cannot  rise  far,  before  it  is  con- 

*  Some  ingenious  experiments  in  confirmation  of  the  theory  of  Count  Rura- 
ford,  by  Lieut.  W.  M.  Mather,  are  detailed  in  Silliman's  Jour.  xii.  368. 


DISTRIBUTION    OF   CALORIC.  43 

densed.     Hence  the  vibration   and  singing  observed  at  this  time. — 
Hare's  Minutes. 

The  slow  conducting  power  of  water  can  be  shown  by  cementing 
an  air  thermometer  into  a  glass  funnel,  and  covering  the  bulb  of  the 
instrument  with  water.  If  now  a  small  quantity  of  ether  be  poured 
upon  the  surface  of  the  water,  it  may  be  fired  without  sensibly  affect- 
ing the  fluid  in  the  stem  of  the  thermometer. 

Conducting  powers  of  ceriform  bodies. 

It  is  extremely  difficult  to  estimate  the  conducting  power  of  aeri- 
form fluids.  Their  particles  move  so  freely  on  each  other,  that  the 
moment  a  particle  is  dilated  by  caloric,  it  is  pressed  upwards  with 
great  velocity  by  the  descent  of  colder  and  heavier  particles,  so  that 
an  ascending  and  descending  current  is  instantly  established.  Be- 
sides, these  bodies  allow  a  passage  through  them  by  radiation.  Now 
the  quantity  of  caloric  which  passes  by  these  two  channels  is  so  much 
greater  than  that  which  is  conducted  from  particle  to  particle,  that 
we  possess  no  means  of  determining  their  proportion.  It  is  certain, 
however,  that  the  conducting  power  of  gaseous  fluids  is  exceedingly 
imperfect,  probably  even  more  so  than  that  of  liquids. — Turner. 

REFERENCES.  Soquet  on  the  power  of  Fluids  as  cojiductors  of  Heat,  in 
Rep.  of  Art$t  1st  ser.  xiii.  277.  Dalton  on  the  same  subject,  in  Rep.  of  Arts, 
%d  ser.  ii.  282.  Dulong  and  Petit  on  the  Laws  of  the  communication  of  Heat, 
in  Ann.  of  Phil.  xiii.  112.  Murray's  Experiments  on  the  conducting  power 
of  Liquids. — Syst.  of  Chem.  1. 

SECTION  III. 

DISTRIBUTION    OP    CALORIC. 

Different  theories  have  been  proposed  to  account  for  the  tendency 
of  bodies  to  acquire  an  equilibrium  of  temperature.  I  shall  content 
myself  with  an  exposition  of  the  theory  of  Professor  Prevost,  of  Ge- 
neva, which  though  not  wholly  free  from  objection,  is  now  very  gene- 
rally adopted.  It  is  altogether  founded  upon  the  phenomena  of  ra- 
diant caloric. 

There  appears  to  be  no  point  of  temperature  at  which  radiant  ca- 
loric is  not  given  out  by  bodies.  Ice,  which  is  so  cold  when  in  con- 
tact with  the  hand  at  ordinary  temperatures,  becomes  hot  if  it  be  trans-- 
ported to  a  chamber  whose  temperature  is  20°  below  zero,  and  a  mass 
of  melting  ice  then  presented  to  the  thermometer  will  cause  the  fluid 
to  ascend  as  well  as  the  vessel  of  boiling  water  presented  to  it  at  the 
ordinary  temperature.  Again,  a  mixture  of  snow  and  salt  cooled 
down  to  20°  below  zero,  becomes  a  hot  body  if  it  be  transported  to 
an  atmosphere  of  40°  below  zero. 

In  all  these  cases,  as  in  our  own  sensations,  there  is  nothing  abso- 
lute ;  all  is  elative.  We  are  therefore  forced  to  the  conclusion  that 
all  bodies,  atrall  temperatures,  radiate  caloric  ;  but  that  the  radiation 
is  of  unequal  intensity,  according  to  their  nature,  to  their  surfaces, 
and  to  the  temperature  to  which  they  are  brought.  The  constancy 
of  the  temperature  of  a  body  depends  then  upon  an  equality  in  the 
quantity  of  radiant  caloric  which  it  emits  and  receives  during  the  same 
time  ;  and  the  equilibrium  of  caloric  which  takes  place  among  several 
bodies  by  mutual  radiation,  depends  upon  the  perfect  compensation 
of  the  instantaneous  changes  which  are  effected  between  all  and  each 


44  EISTRIBUTION    OF    CALORIC. 

of  them.  This  is  the  ingenious  theory  suggested  by  Prevost,  and 
which,  combined  with  the  peculiar  properties  of  different  surfaces,  ex- 
plains all  the  phenomena  of  radiant  caloric. 

A  few  experiments  will  more  fully  illustrate  this  interesting  subject. 
Place  a  thermometer  in  a  chamber  which  has  an  equal  temperature 
in  all  its  parts,  and  allow  it  to  remain  until  it  becomes  of  the  same 
temperature.  In  the  same  chamber  have  an  opake  disk  of  any  na- 
ture and  form  whatever,  also  at  the  same  temperature.  If  now  this 
disk  be  presented  at  a  greater  or  less  distance  to  the  bulb  of  the  ther- 
mometer, no  effect  will  be  produced  upon  it.  The  reason  is  obvious. 
Before  we  employed  the  disk,  the  bulb  received  at  each  instant  from 
the  walls  and  from  the  air  of  the  chamber,  a  certain  quantity  of  heat 
by  radiation  and  reflection,  and  itself  at  the  same  time,  sent  back 
by  this  double  mode  an  amount  exactly  equal,  since  its  temperature 
remained  the  same.  Now  when  we  present  the  opaque  disk  to  the 
bulb  of  the  thermometer,  we  intercept  for  each  point  of  the  bulb  all 
the  calorific  rays  which  are  comprised  in  the  cone  formed  by  this 
point,  and  the  whole  surface  of  the  disk.  But,  in  exchange,  the  same 
point  receives  from  the  disk  a  certain  number  of  rays  comprised  in  the 
cone  just  mentioned  ;  and  in  consequence  of  the  supposed  equality  of 
temperature,  this  number  is  exactly  equal  to  that  which  came  from 
that  portion  of  the  wall  upon  which  the  disk  is  projected.  Thus  after 
the  interposition  of  the  disk,  each  point  of  the  bulb  receives  still  as 
much  heat  in  the  same  time,  as  it  received  previously  ;  and  as  the 
quantity  which  it  gives  out  is  not  changed,  it  is  evident  that  its  tem- 
perature and  that  of  the  bulb  will  remain  the  same. 

A  different  result,  however,  will  be  observed,  if  there  be  presented 
to  the  thermometer  a  disk  whose  temperature  is  either  higher  or  lower 
than  that  of  the  chamber;  for  then  the  number  of  caloritic  rays  radi- 
ated or  reflected  by  this  disk  in  a  given  time  will  be,  in  the  former  case 
greater,  in  the  latter,  less  than  that  which  came  from  the  portion  of 
the  wall  which  it  conceals. 

The  same  explanation  will  apply  in  the  cases  where  two  mirrors  are 
employed.  Place  a  thermometer,  the  bulb  of  which  is  blackened,  in 
the  focus  of  one  mirror,  and  allow  it  to  become  of  the  same  tempera- 
ture as  the  surrounding  air,  and  in  the  focus  of  the  other  mirror, 
place  any  body  which  is  of  the  same  temperature.  The  thermometer 
will  not  be  affected.  The  reason  will  be  readily  perceived.  When 
the  passage  of  the  rays  through  this  last  focus  was  free,  there  arrived 
at  this  point  from  all  parts  of  space  a  certain  number  of  calorific 
rays,  which,  after  they  have  crossed,  fall  upon  the  second  mirror,  are 
reflected  from  it  to  the  first,  and  finally  are  concentrated  upon  the 
bulb  of  the  thermometer.  These  rays  are  indeed  intercepted  by  the 
opaque  body  which  we  have  placed  in  the  focus,  but  as  this  is  sup- 
posed to  be  of  the  same  temperature  with  the  surrounding  space,  it 
transmits  by  radiation  and  reflection  a  number  of  rays  exactly  equal, 
which  falling  upon  the  second  mirror  are  reflected  to  the  first,  and 
finally  to  the  thermometer ;  and  hence  no  change  is  effected.  But 
this  will  not  be  the  case  when  the  body  placed  in  the  focus  is  either  of 
a  higher  or  lower  temperature  than  that  of  the  surrounding  space  and 
of  the  thermometer.  For  then  the  thermometer,  after  the  interpo- 
sition, will  receive  through  the  medium  of  the  mirrors  more  or 
less  than  it  received  before,  and  also  more  or  less  than  it  loses  in 
the  same  time  either  by  reflection  or  by  radiation.  Whence  it  fol- 
lows, that  the  temperature  will  b^  elevated  in  the  former  case,  and  re- 
duced in  the  latter. 


DISTRIBUTION   OF   CALORIC.  45 

These  views  are  fully  confirmed  by  experiment.  For  as  has  al- 
ready been  shown,  if  we  place  a  hot  body  in  the  focus  of  one  mirror, 
the  thermometer  in  the  focus  of  the  opposite  one  will  indicate  an  in- 
crease of  temperature  ;  and  on  the  contrary,  if  we  place  a  piece  of 
ice  or  a  mixture  of  snow  and  salt  in  the  focus  of  one  mirror,  the 
thermometer  in  the  focus  of  the  opposite  mirror  will  indicate  a  di- 
minution of  temperature.  All  these  phenomena  can  be  explained  if 
we  only  admit  that  all  bodies,  however  low  their  temperature,  radiate 
caloric,  and  in  this  there  is  nothing  surprising,  since  our  ideas  of  heat 
and  cold  are  all  relative.  Without  this  admission  we  should  have  to 
adopt  the  opinion  advanced  by  some  philosophers,  that  cold  as  well  as 
heat  is  radiated  ;  an  opinion  which  is  not  necessary,  nor  even  war- 
ranted by  the  facts.  Biot.  Precis.  Elemental™,  ii.  642. 

The  theory  of  radiation  as  thus  unfolded,  has  been  successfully  em- 
ployed by  Dr.  Wells,  in  explaining  the  phenomena  of  Dew.  By  his 
numerous  and  well  directed  experiments  he  has  amply  proved,  that 
the  formation  of  dew  is  owing  to  the  radiation  of  caloric  from  the 
ground,  and  he  conceives  that  all  the  previous  explanations  fail  in  not 
accounting  for  the  production  of  cold  in  the  dewed  body.  He  has 
shown  that  the  degree  of  cold  on  the  surface  of  grass,  &c.  is  in  pro- 
portion to  the  quantity  of  dew  which  is  formed  : — that  dew  appears 
in  the  greatest  quantity  upon  those  substances  which  radiate  the  most 
caloric  ; — that  the  radiation  is  the  greatest,  and  the  dew  most  copious 
in  calm  and  serene  nights ;  that  the  process  is  diminished  or  sus- 
pended by  high  winds  and  by  the  presence  of  clouds  ;  and  that  in 
those  cases  the  temperature  of  the  grass,  &c.  is  the  same  as  that  of 
the  air. —  Wells'  Essay  on  Dew,  4»c. 

A  similar  explanation  has  been  applied  by  Dr.  Wells  to  various  ap- 
pearances connected  with  dew,  and  among  these  not  the  least  curi- 
ous is  that  of  the  formation  of  ice  during  the  night  in  Bengal,  when 
the  temperature  of  the  air  is  above  32°  F.  This  has  generally 
been  ascribed  to  cold  produced  by  evaporation  ;  an  opinion  which 
has  been  adopted  by  Davy,  Leslie,  Thomson  and  others.  Dr.  Wells, 
however,  has  shown  conclusively,  that  it  cannot  be  owing  to  this 
cause ;  but  that  it  depends  upon  the  radiation  of  heat  to  the  heavens. 
For  it  is  observed  that  ice  is  chiefly  formed  in  Bengal  during  the 
clearest  and  calmest  nights,  when  the  greatest  cold  from  radiation  is 
observed  on  the  surface  of  the  earth ;  and  that  clouds  and  winds  pre- 
vent its  formation  by  preventing,  or  at  least  diminishing,  the  radiation 
of  heat.* 

The  study  of  the  laws  of  radiant  caloric  has  lead  to  impor- 
tant improvements  in  the  construction  of  fire  places ;  a  subject 
which  engaged  the  attention  of  Count  Rumford. — See  Rumford's 
Essays. 

*  Captain  Scoresby  found  that  in  the  Polar  Seas,  ice  was  formed  in  clear 
nights  when  the  temperature  of  the  air  was  several  degrees  above  the  freez- 
ing point  of  water;  but  that  in  cloudy  nights  no  ice  was  formed — the  tem- 
perature of  the  air  in  both  cases  being  the  same.  In  the  last  instance  there 
was  a  constant  interchange  of  caloric  between  the  water  and  the  clouds,  by 
means  of  which  the  temperature  of  the  water  was  preserved  nearly  equal  to 
the  temperature  of  the  air,  which  was  above  the  freezing  point.  In  the  first 
instance,  as  there  was  nothing  which  could  radiate  back  to  the  water  the  ca- 
loric which  was  radiated  from  it,  its  temperature  sunk  below  the  freezing 
point,  and  ice  was  formed. 

D 


46  EFFECTS   OF   CALORIC. 

REFERENCES. — Prevost's  Researches  svr  la  Chaleur.  Wells1  Easy  on 
Dew,  Spc.  Pictefs  Essays.  Biofs  Precis.  Elementaire.  Sundry  papers 
on  Prevosfs  Theory  of  Radiant  Caloric,  by  R.  Davenport,  Prof.  Prevost, 
Dr.  Wells  andJ.  Murray,  are  contained  in  the  Ann.  of  Phil.  v.  vi.  and  vii. 

SECTION  IV. 
EFFECTS   OF   CALORIC. 

The  general  effects  of  caloric  are  — 

1.  EXPANSION. 

2.  LIQUEFACTION. 

3.  VAPORIZATION. 

EXPANSION. 

This  is  one  of  the  most  remarkable  effects  of  caloric.  When  bodies 
are  heated  they  become  less  compact,  are  increased  in  bulk,  or  in 
other  words,  expand  ;  and  as  they  cool  they  retuin  to  their  former  di- 
mensions. Hence  caloric  is  inferred  to  separate  their  particles,  and 
is  regarded  as  the  repulsive  power,  which  is  constantly  opposed  to  co- 
hesion. This  being  the  case,  it  follows  that  caloric  must  produce  the 
greatest  expansion  in  those  bodies  whose  cohesive  power  is  the  least; 
and  the  inference  is  justified  by  observation.  Thus  the  force  of  co- 
hesion is  greatest  in  solids,  less  in  liquids,  and  least  of  all  in  seriform 
substances  ;  while  the  expansion  of  solids  is  trifling,  that  of  liquids  is 
more  considerable,  and  that  of  elastic  fluids  far  greater. 

Expansion  of  Solids. 

In  proof  of  the  expansion  of  solids,  we  need  only  take  the  exact 
dimensions  in  length,  breadth,  and  thickness  of  any  substance  when 
cold,  and  measure  it  again  when  strongly  heated,  when  it  will  be 
found  to  have  increased  in  every  direction.  A  familiar  demonstration 
of  the  fact  may  be  afforded  by  adapting  a  ring  to  an  iron  rod,  the  for- 
mer being  just  large  enough  to  permit  the  latter  to  pass  through  it 
while  cold.  The  rod  is  next  heated,  and  will  then  no  longer  pass 
through  the  ring.  This  dilatation  from  heat  and  consequent  contrac- 
tion in  cooling  takes  place  with  a  force  which  appears  to  be  irre- 
sistible. 

This  property  of  metals  has  been  applied  to  various  useful  purposes. 
The  iron  band  or  tire,  as  it  is  called,  of  a  carriage-wheel,  being  pur- 
posely made  a  little  smaller  than  the  wooden  circle,  is  enlarged  by 
heat  so  as  to  embrace  the  latter,  and  being  then  suddenly  cooled,  by 
throwing  water  upon  it,  is  again  contracted,  and  becomes  immoveably 
fixed.  An  ingenious  use  of  the  same  principle  was  made,  several  years 
ago,  at  Paris,  by  M.  Molard,  in  restoring  to  the  perpendicular,*  two 
opposite  walls  of  a  building,  which  had  been  pressed  outward  by  the 
incumbent  weight.  Through  strong  holes  in  the  walls,  opposite  to . 
each  other,  several  strong  iron  bars  were  introduced,  so  as  to 
cross  the  apartment,  and  to  project  outside  the  building  sufficiently 
to  allow  strong  iron  plates  or  washers  to  be  screwed  upon  their  ends. — 
The  bars  were  then  heated,  and  the  iron  plates  screwed  up.  On 
cooling,  the  bars  contracted,  and  drew  the  separated  walls  together  ; 
and  this  was  repeated  till  the  walls  had  regained  their  perpendicular 
position. 


EFFECTS   OF   CALORIC.  47 

In  riveting  together  the  iron  plates  out  of  which  steam  engine 
boilers  are  made,  it  is  necessary  to  produce  as  close  a  joint  as  possible. 
This  is  effected  by  using  the  rivets  red  hot ;  while  they  are  in  that 
state  the  two  plates  of  iron  are  rivetted  together,  and  the  contraction 
which  the  rivet  undergoes  in  cooling  draws  them  together  with  a 
force  which  is  only  limited  by  the  tenacity  of  the  metal  of  which  the 
rivet  itself  is  made. 

The  degree  of  expansion,  however,  is  not  the  same  for  all  solids, 
and  even  differs  materially  in  substances  of  the  same  class.  Thus 
the  metals  expand  in  the  following  order,  the  most  expansible  being 
placed  first,  zinc,*  lead,  tin,  copper,  bismuth,  iron,  steel,  antimony, 
palladium,  platinum.  The  experiments  of  Petit  and  Dulong,  (Ann.  of 
Phil.  xiii.  164,)  tend  to  show  that  unequal  degrees  of  expansion  are 
produced  in  a  bar  of  metal  by  a  succession  of  similar  increments  of 
heat ;  the  rate  of  expansion  increasing  with  the  temperature. 

The  expansion  of  solids  has  occupied  the  attention  of  many  experi- 
menters, whose  chief  object  appears  to  have  been  to  ascertain  the 
exact  quantity  that  different  substances  are  lengthened,  by  a  given 
increase  of  heat,  and  to  determine  whether  or  not  their  expansion  is 
equable  at  different  temperatures.  The  Philosophical  Transactions 
of  London  contain  the  various  dissertations  on  this  subject  by  Elli- 
cott,  Smeaton,  Troughton  and  General  Roy  :  and  Biot  in  his  Traite 
de  rhysique,  i.  158,  has  given  the  results  of  experiments  performed 
with  great  care  by  Lavosier  and  La  Place.  [A  table  of  the  linear 
dilatation  of  various  solids  by  heat  will  be  found  in  lire's  Dictionary 
of  Chemistry,  and  in  the  Library  of  Useful  Knowledge.] 

Expansion  of  Liquids. 

The  simplest  method  of  proving  the  expansion  of  liquids  is  by  put- 
ting a  common  thermometer,  made  with  mercury  or  alcohol,  into 
warm  water,  when  the  dilatation  of  the  liquid  will  be  shown  by  its 
ascent  in  the  stem.  The  experiment  is  indeed  illustrative  of  two 
other  facts.  It  proves,  first,  that  the  dilatation  increases  with  the 
temperature  ;  for  if  the  thermometer  is  plunged  into  several  por- 
tions of  water  heated  to  different  degrees,  the  ascent  will  be  great- 
est in  the  hottest  water,  and  least  in  the  coolest  portions.  It  demon- 
strates, secondly,  that  liquids  expand  more  than  solids.  The  glass 
bulb  of  the  thermometer  is  itself  expanded  by  the  hot  water,  and 
therefore  is  enabled  to  contain  more  mercury  than  before  ;  but  the 
mercury  being  dilated  to  a  much  greater  extent,  not  only  occupies  the 
additional  space  in  the  bulb,  but  likewise  rises  in  the  stem.  Its  as- 
cent marks  the  difference  between  its  own  dilatation  and  that  of  the 
glass,  and  is  only  the  apparent,  not  the  actual  expansion  of  the  li- 
quid.—  Turner. 

Liquids  differ  also  in  their  relative  expansibilities  ;  ether  is  more 
expansible  than  alcohol  ;  alcohol  more  than  water,  and  water  more 
than  mercury.  Those  liquids  are  generally  most  expansible  which 
boil  at  the  lowest  temperature. 

*  This  is  the  order  usually  given,  but  according  to  Dr.  Lardner,  lead  is  the 
most  expansible  of  the  rnotals,  In  the  solid  state.  Its  bulk  is  increased  one 
part  in  350  by  being  plunged  into  inching  ice,  and  the  ire  then  being  raised 
to  the  temperature  of  boiling  water;  or  in  o'.her  words,  this  takes  place  bv  a 
change  of  temperature,  amouM'ing  to  130  degrees  of  the  common  thermome- 
ter.— Treatise  on  Heat}  23. 


48  EFFECTS   OF   CALORIC. 

Exp.  This  may  be  rendered  evident  by  partially  filling  several  glass 
tubes  of  equal  diameter,  furnished  with  bulbs,  with  the  different  liquids 
and  placing  them  in  hot  water  ;  as  the  liquids  expand,  they  will  rise  to 
different  heights  in  the  tubes.  To  render  this  more  apparent,  the  li- 
quids may  be  tinged  with  some  colouring  matter. 

The  expansion  of  various  liquids  by  heat  has  been  studied  with  great 
care  by  Lavoisier  and  La  Place,  Petit  and  Dulong. 

Expansion  of  JEriform  bodies. 

The  expansion  of&riform  bodies  by  heat  may  be  exemplified  by  hold- 
ing near  the  fire  a  bladder  half  filled  with  air,  the  neck  of  which  is 
closely  tied,  so  as  to  prevent  the  enclosed  air  from  escaping.  The 
bladder  will  soon  be  fully  distended,  and  may  even  be  burst  by  con- 
tinuing and  increasing  the  heat.  All  aeriform  bodies,  when  deprived  of 
moisture,  and  even  condensible  vapours,  when  not  in  contact  with  the 
liquids  from  which  they  have  been  produced,  undergo  the  same  expan- 
sion or  contraction  at  all  temperatures  hitherto  tried,  by  similar  ad- 
ditions or  subtractions  of  caloric.  This  for  a  single  degree  of  Fahr- 
enheit's thermometer,  is  ^g-g-  part  of  their  bulk,  between  32  and  212C? 
as  first  determined  by  Mr.  Dalton,  and  afterwards  confirmed  by  Gay 
Lussac,  and  by  Petit  and  Dulong,  who  have  extended  the  law,  up  to 
572°  F.  (Ann.  of  Phil,  xxix.  117.)  This  equable  expansion  of  air  by 
equal  increments  of  heat,  adapts  it  for  the  accurate  measurement  of 
temperature.  At  a  cherry  red  heat,  (=  about  1035  F.)  Sir  H.  Davy 
found  that  a  volume  of  air  =  1  at  212°  F.  became  2.5  volumes. — On 
Flame,  68.  Henry's  Chem.  i.  91. 

To  the  general  law  of  the  expansion  of  bodies  by  heat7  and  their 
contraction  by  cold,  there  are,  however,  some  remarkable  exceptions. 
Thus  water  when  cooled  down  below  the  temperature  of  39°  F.  ex- 
pands and  continues  to  do  so,  until  it  is  converted  into  ice.*  The 
most  remarkable  circumstance  attending  this  expansion  is  the  pro- 
digious force  with  which  it  is  effected.  The  Florentine  academicians 
burst  a  hollow  brass  globe,  whose  cavity  was  only  an  inch  in  diameter. 
by  freezing  the  water  with  which  it  was  filled  :  and  it  has  been  esti- 
mated that  the  expansive  power  necessary  to  produce  such  an  effect  is 
equal  to  a  pressure  of  27,720  pounds  weight.  This  fact  was  confirm- 
ed by  the  experiments  of  Major  Williams  of  Quebec. — Trans.  Royal 
Society,  Edin.  ii.  23. 

Salts  also,  in  the  act  of  crystallizing,  expand  ;  and  some  of  the  me- 
tals, as  cast  iron,  bismuth  and  antimony,  have  their  dimensions  en- 
larged on  congealing.  Hence  the  precision  with  which  ca^t  iron  takes 
the  impression  of  the  mould ;  and  hence  also  the  use  of  antimony  to 
the  type  founder.  In  all  these  cases,  the  cause  of  the  expansion  is 
supposed  to  be  the  new  and  peculiar  arrangement  of  its  particles.  It 
only  occurs  in  those  bodies  which  upon  cooling  assume  a  crystalline 
or  semi-crystalline  form, — the  particles  of  which,  then  occupy  more 
space  than  when  they  are  liquid.  In  the  case  of  water,  where  the  ex- 
pansion commences  previous  to  congelation,  it  is  supposed  that  the 
water  begins  to  arrange  itself  in  the  order  it  will  assume  in  the  solid 
state,  before  actually  laying  aside  the  liquid  form.  If  these  views  are 
correct,  the  exceptions  to  the  general  law  of  expansion  by  heat  are 
rather  apparent  than  real. 


*  The  mean  of  the  recent  determinations  of  the  true  point  of  the  maximum 
density  of  water  by  Stampfer,  Mu-icke  and  Crichton  is  38.34.— Johnston's 
Report  on  Chemistry. 


EFFECTS    OF   CALORIC.  49 

One  of  the  important  applications  of  the  principle  of  expansion  is 
to  the  construction  of  instruments  which,  under  the  designation  of 
thermometers,  or  thermoscopes,  pyrometers,  or  pyroscopcs,  are  now  in 
general  use  in  every  part  of  the  civilized  world.  Their  names  are  de- 
rived from  the  Greek  terms,  thermos,  pur,  signifying  heat,  fire,  and  mc- 
tron,  skopos,  a  measure,  an  investigator. 

Thermometers. 

The  invention  of  the  thermometer  is  generally  ascribed  to  Sanc- 
torio  of  Padua,  who  flourished  about  the  beginning  of  the  seventeenth 
century.  But  the  instrument  employed  by  that  philosopher,  was  of 
a  very  simple  kind,  and  measured  variations  of  temperature  by  the 
variable  expansion  of  a  confined  portion  of  air.  To  prepare  it,  a 
glass  tube  is  to  be  provided,  eighteen  inches  long,  open  at  one  end, 
and  blown  into  a  ball  at  the  other.  On  applying  a  warm  hand  to 
the  ball,  the  included  air  expands,  and  a  portion  is  expelled  through 
the  open  end  of  the  tube.  In  this  state  the  aperture  is  quickly 
inverted  in  a  cup  filled  with  any  coloured  liquid,  which  ascends  into 
the  tube  as  the  air  in  the  ball  contracts  by  cooling.  The  instrument 
is  now  prepared.  An  increase  of  temperature  forces  the  liquor  down 
the  tube ;  and  on  the  contrary,  the  application  of  cold  causes  its  as- 
cent. These  effects  may  be  exhibited  alternately  by  applying  the 
hand  to  the  ball,  and  theji  blowing  on  it  with  a  pair  of  bellows.  By 
the  application  of  a  graduated  scale,  the  amount  of  expansion  may 
be  measured. 

The  advantages  of  the  Air  Thermometer  consists  in  the  great  amount 
of  the  expansion  of  air,  which  by  a  given  elevation  of  temperature,  is 
increased  in  bulk  above  twenty  times  more  than  mercury.  Hence  it  is 
adapted  to  detect  minute  changes,  which  the  mercurial  thermometer 
would  scarcely  discover ;  and  its  expansions  being  uniform  for  equal 
additions  of  caloric,  it  is  better  adapted  than  any  liquid  for  becoming, 
when  properly  applied,  an  accurate  measure  of  temperature.  But  an 
insuperable  objection  to  it,  in  its  present  form  is,  that  it  is  affected  not 
only  by  changes  of  temperature,  but  by  variations  of  atmospheric 
pressure. 

An  ingenious  modification  of  the  air  thermometer  has  been  invented 
by  Mr.  Leslie  and  employed  by  him,  with  great  advantage,  in  his  in- 
teresting researches  respecting  heat.  To  this  instrument  he  has  given 
the  name  of  the  Differential  Thermometer.  It  consists  of  two  thin 
glass  balls  joined  together  by  a  tube  bent  nearly  into  the  shape  of  the 
letter  U.  Both  balls  contain  air,  but  the  greater  part  of  the  tube  is  fill- 
ed with  sulphuric  acid  coloured  with  carmine.  It  is  obvious  that  this 
instrument  cannot  be  affected  by  any  change  of  temperature  acting 
equally  on  both  balls  ;  for  as  long  as  the  air  within  them  expands  or 
contracts  to  the  same  extent,  the  pressure  on  the  opposite  surfaces  of 
the  liquid,  and  consequently  its  position,  will  continue  unchanged. 
Hence  the  differential  thermometer  stands  at  the  same  point,  how- 
ever different  may  be  the  temperature  of  the  medium.  But  the  slight- 
est difference  between  the  temperature  of  the  two  balls  will  instantly 
be  detected  ;  for  the  elasticity  of  the  air  on  one  side  being  then  greater 
than  that  on  the  other,  the  liquid  will  retreat  towards  the  ball  whose 
temperature  is  lowest.  It  is  hence  admirably  adapted  to  ascertain  the 
difference  of  the  temperatures  of  two  contiguous  spots  in  the  same  at- 
mosphere ;  for  example,  to  determine  the  heat  in  the  focus  of  a  concave 
reflector. — Sec  Leslie's  Essay  on  Heat. 

A  differential  thermometer  has  been  contrived  by  Dr.  Howard  of 


50  EFFECTS  OF   CALORIC. 

Baltimore,  resembling  that  of  Mr.  Leslie  in  its  general  form,  but  in 
which  the  degree  of  heat  is  measured  by  the  expansive  force  of  the 
vapour  of  ether  or  alcohol  in  vacua.  It  is  intended  to  be  applied  to  the 
same  purposes  as  that  of  Mr.  Leslie,  but  is  a  much  more  delicate  in- 
strument.— Brands s  Jour.  viii.  219. 

.Thermometers  filled  with  alcohol  or  spirit  of  wine,  (a  liquid  which 
lias  not  been  congealed  by  any  degree  of  cold  hitherto  produced,)  are 
best  adapted  to  the  measurement  of  very  low  temperatures,  at  which 
mercury  would  freeze.  The  amount  of  the  expansion  of  alcohol  also, 
which  exceeds  that  of  mercury  above  eight  times,  fits  it  for  ascertain- 
ing very  slight  variations  of  temperature.  But  it  cannot  be  applied  to 
measure  high  degrees  of  heat,  because  the  conversion  of  the  spirit  into 
vapour  would  burst  the  instrument. — Henry,  i.  96. 

The  fluid  best  adapted  for  filling  thermometers  is  mercury,  which, 
though  it  expands  less  in  amount  than  air  or  alcohol,  still  undergoes 
this  change  to  a  sufficient  degree  ;  and  in  consequence  of  its  difficult 
conversion  into  vapour,  may  be  applied  to  the  admeasurement  of  more 
elevated  temperatures. 

In  the  construction  of  thermometers  the  first  object  is  to  select  a 
tube  with  a  small  bore,  the  diameter  of  which  is  the  same  throughout 
its  whole  length  ;  and  then  by  melting  the  glass  to  blow  a  bulb  at  one 
end  of  it.  The  bulb  is  now  heated,  by  means  of  which  the  air  within, 
it  is  rarified  ;  and  the  open  end  of  the  tube  is  dipped  into  mercury. 
As  the  air  cools  and  contracts,  the  mercury  is  forced  up,  entering  the 
bulb,  to  supply  the  place  of  the  air  which  has  been  expelled  from  it- 
Only  a  part  of  the  air,  however,  is  removed  by  this  means  ;  the  re- 
mainder is  driven  out  by  the  ebullition  of  the  mercury. 

Having  thus  contrived  that  the  bulb  and  about  one-third  of  the  tube 
shall  be  full  of  mercury,  the  next  step  is  to  seal  the  open  end  hermet- 
ically. This  is  done  by  heating  the  bulb  till  the  mercury  rises  very 
near  the  summit,  and  then  suddenly  darting  a  fine  pointed  flame  from 
a  blow-pipe  across  the  opening,  so  as  to  fuse  the  glass  and  close  the 
aperture,  before  the  mercury  has  had  time  to  recede  from  it. 

The  graduation  of  the  thermometer,  by  which  alone  the  observa- 
tions made  with  different  instruments  can  be  compared  together,  con- 
sists of  two  parts,  viz.  first  to  obtain  two  fixed  points  which  shall  be 
the  same  in  every  thermometer  :  and  second,  to  divide  the  interval  be- 
tween these  two  fixed  points  into  any  number  of  equal  parts  or  de- 
grees. To  effect  the  first  of  these  objects,  the  practice  generally  pur- 
sued, is  that  introduced  by  Sir  Isaac  Newton,  and  is  founded  on  the 
fact  that  when  a  thermometer  is  plunged  into  ice  that  is  dissolving,  or 
into  water  that  is  boiling,  it  constantly  stands  at  the  same  elevations 
in  all  countries,  provided  there  is  a  certain  conformity  of  circumstan- 
ces. The  point  of  congelation,  or  the  freezing  point,  is  ascertained  by 
immersing,  in  thawing  snow  or  ice,  the  ball  and  part  of  the  stem  ;  so 
that  the  mercury  when  stationary,  shall  barely  appear  above  the  sur- 
face. At  this  place  let  a  mark  be  made  with  a  file. 

To  fix  the  boiling  point  is  a  more  delicate  operation,  since  the  tem- 
perature, at  which  water  boils  is  affected  by  various  circumstances, 
which  will  be  more  particularly  mentioned  hereafter.  The  general 
directions  are,  that  the  water  be  perfectly  pure,  free  from  any  foreign 
particles,  and  not  above  an  inch  in  depth — the  ebullition  brisk,  and 
conducted  in  a  deep  metallic  vessel,  so  that  the  stern  of  the  ther- 
mometer may  be  surrounded  by  an  atmosphere  of  steam,  and  thus 
exposed  to  the  same  temperature  as  the  bulb — that  the  vapour  be  al- 
lowed to  escape  freely — and  the  barometer  to  stand  at  30  inches* 


EFFECTS    OF   CALORIC.  51 

The  second  part  of  the  process,  or  the  division  of  the  interval  be- 
tween the  two  fixed  points,  may  be  effected  by  marking  on  the  tube 
itself,  by  means  of  a  diamond,  or  by  first  drawing  the  divisions  upon 
a  piece  of  paper,  ivory  or  metal,  and  afterwards  attaching  it  to  the 
thermometer.  The  number  of  divisions  between  these  two  points  is 
not  material,  though  it  would  be  more  convenient  if  there  was  greater 
uniformity  in  this  respect.  In  the  centigrade  thermometer,  which  is 
perhaps  the  most  convenient,  this  space  is  divided  into  100 3,  the 
freezing  of  water,  being  marked  (P,  the  boiling  point  100^.  In  the 
scale  of  Reaumur  the  freezing  point  is  0D,  the  boiling  point  S0\  And 
in  Fahrenheit's  scale,  generally  employed  in  England  and  America, 
the  interval  is  divided  into  180°  ;  but  the  zero  of  Fahrenheit  is  placed 
32°  below  the  temperature  of  melting  snow,  and  on  this  account  the 
point  of  ebullition  is  212°.  The  temperature  expressed  by  one  of 
these  scales  can  easily  be  reduced  to  that  of  another,  by  knowing  the 
relation  which  exists  between  their  degrees. — See  Turner  and  Webster's 
Brande,  also  L.  U.  K.  Art.  Heat,  17. 

P  EFERENCES.  Particular  directions  for  the  construction  of  Thermometers 
— Henry's  Cke.m,  i.  96.  The  Chevalier  Landrianfs  directions  for  construct' 
ing  Thermometers  of  great  sensibility — Brandos  Jour.  vii.  183.  Directions 
for  determining  the  accuracy  of  Thermometers — Faraday's  Cheni.  Manip. 
Library  of  Useful  Knowledge — Thermometer  and  Pyrometer.  The  article 
Thermometer  in  the  Edinburgh  Encyclopaedia — Prof.  Forbes1  Report  on  Me- 
teorology, to  the  British  Association,  1832. 

Pyrometers.  These  are  instruments  for  measuring  degrees  of  heat 
much  higher  than  those  which  can  be  determined  by  the  mercurial 
thermometer.  Of  these,  there  are  several.  That  of  Mr.  Wedgewood 
is  founded  upon  the  property  which  clay  posse  ses  of  contracting 
when  strongly  heated,  without  returning  to  its  former  dimensions  as  it 
cools.  But  the  indications  of  this  instrument  cannot  be  relied  on, 
and  it  is  at  present,  seldom  employed.  The  best  pyrometer  is  per- 
haps that  of  Mr.  Danieli.  A  bar  of  platinum  is  enclosed  in  a  case 
made  of  the  same  ware  as  black  lead  crucibles,  and  is  fixed  to  it  at 
one  end,  while  the  other  is  left  free  to  move  an  index,  by  which  means 
degrees  of  heat,  above  ignition,  admit  of  being  measured,  but  not  with 
accuracy,  owing  to  the  increasing  rate  of  expansion  in  metals  at  high 
temperatures. — Henry,  i.  92.  Brande  s  Jour.  xi.  309. 

On  the  same  principle  Breguet  has  constructed  a  very  sensible 
metallic  thermometer,  for  temperatures  between  the  freezing  and 
boiling  points  of  water.  It  consists  of  a  slip  of  silver  and  another  of 
platinum,  united  face  to  face  with  solder,  and  coiled  into  a  spiral,  one 
end  of  which  is  fixed,  while  the  other  is  connected  with  an  index 
which  moves  over  a  circular  graduated  plate.  Strictly,  two  metals 
only  are  sufficient  for  the  purpose,  platinum  and  silver,  for  instance ; 
but  it  has  been  found  to  be  an  improvement  to  employ  three,  and  the 
instrument  is  now  prepared  by  interposing  between  the  platinum 
and  silver  a  metal  of  mean  dilatability,  such  as  pure  gold.  The 
•  unequal  expansion  of  the  metals  causes  the  spiral  to  increase  or 
diminish  the  degree  of  its  curvature  by  variations  of  temperature  ; 
and  the  needle,  being  attached  at  right  angles  to  the  axis  of 
the  spiral,  is  thus  made  to  traverse  the  graduated  circle.  Experi- 
ments have  shown  that  the  needle,  for  equal  changes  of  temperature, 
moves  over  equal  arcs,  so  that  the  instrument  is  comparable,  not  only 
with  itself,  but  with  others  constructed  on  the  same  principle.  Such 


52  EFFECTS   OF   CALORIC. 

was  found  to  be  its  great  sensibility,  that,  when  enclosed  in  a  large 
receiver,  which  was  rapidly  exhausted  by  the  air  pump,  it  indicated  a 
reduction  of  temperature  from  66°  F.  to  25°,  (=41°,)  while  a  sensi- 
ble mercurial  thermometer,  similarly  situated,  fell  only  3.6°. — Henry's 
Chem.  i.  92.  Ann.  de  Chim.  et  de  Phys.  v.  312. 

Instruments  have  also  been  constructed  for  the  purpose  of  ascer- 
taining the  highest  and  lowest  temperature  which  has  occurred  during 
a  given  interval  of  time.  These  have  been  called  Register  Thermome- 
ters ;  and  one  of  the  best  is  that  described  by  Dr.  John  Rutherford. — 
Turner's  Chem.  and  L.  U.  K. 

But  though  the  thermometer  is  one  of  the  most  valuable  instru- 
ments of  philosophical  research,  it  is  by  no  means  an  exact  measure 
of  the  number  of  degrees  of  heat  in  a  body.  It  does  not  follow,  be- 
cause the  thermometer  stands  at  the  same  elevation  in  any  two  bod- 
ies, that  they  contain  equal  quantities  of  caloric  ;  nor  should  we  in- 
fer that  the  warmer  possesses  more  of  this  principle  than  the  colder. 
The  thermometer  only  indicates  that  condition  of  a  body  which  is 
expressed  by  the  term  temperature.  All  that  we  learn  by  this  instru- 
ment is,  whether  the  temperature  of  one  body  is  greater  or  less  than 
that  of  another ;  and  the  difference,  if  there  be  any,  is  expressed  nu- 
merically, namely  by  the  degrees  of  the  thermometer.  These  de- 
grees, however,  it  should  be  remembered,  are  merely  parts  of  an  arbi- 
trary scale  which  have  no  reference  whatever  to  the  actual  quantity  of 
caloric  present  in  bodies. 

REFERENCES.  WedgewoocPs  description  of  and  observations  on  his  Py- 
rometer— Repertory  of  Arts,  1st  series,  v.  vi.  yii.  ix.  Gazerarfs  Memoirs  on 
the  method  of  preparing  Pyrometrical  Earths  of  VVedgewood — Same  work, 
1st  series,  xir.  211.  Fourmy  on  the  Thermometer  of  baked  Earth — Same 
\cork,  Zd  series,  vii.  143.  xxii.  309.  L.  U.  K. 

LIQUEFACTION. 

It  has  already  been  shown,  that  as  we  apply  heat  to  a  body,  it  in- 
creases in  bulk.  In  continuing  its  application,  the  enlargement  also 
continues,  till  it  arrives  at  a  certain  temperature,  when  a  change  of 
a  different  nature  ensues.  It  now  becomes  liquid,  and  the  body  is 
said  to  be  melted,  liquified  or  fused,  and  the  change  is  called  fusion, 
or  liquefaction.  On  the  contrary,  when  we  apply  cold  to  a  liquid  it 
contracts,  and  continues  to  do  so  till  at  a  certain  temperature  it  be- 
comes solid,  and  it  is  then  said  to  be  frozen  or  congealed.  In  this  way 
almost  every  fluid  may  be  made  solid  and  almost  every  solid  fluid  ; 
and  both  these  points,  though  different  for  different  bodies,  are  uni- 
formly the  same  under  similar  circumstances  in  the  same  body.  Under 
this  head  the  two  following  general  propositions  may  be  stated  : 

1.  Bodies  in  passing  from  a  solid  to  a  liquid  state,  absorb  caloric. 

If  a  pound  of  water  at  32°  be  mixed  with  a  pound  of  water  at  172°, 
the  temperature  of  the  mixture  will  be  intermediate  between  them, 
or  102°.  But  if  a  pound  of  water  at  172°  be  added  to  a  pound  of 
ice  at  32°,  the  ice  will  quickly  dissolve,  and  on  placing  a  thermome- 
ter in  the  mixture,  it  will  be  found  to  stand,  not  at  102J,  but  at  32°. 
In  this  experiment,  the  pound  of  hot  water,  which  was  originally  at 
172°,  actually  looses  140°  of  caloric,  all  of  which  entered  into  the  ice, 
and  caused  its  liquefaction,  but  did  not  affect  its  temperature  ;  and  it 
follows,  therefore,  that  a  quantity  of  caloric  becomes  insensible  during 


EFFECTS    OF   CALORIC.  53 

the  melting  of  ice,  sufficient  to  raise  the  temperature  of  an  equal  weight 
of  water  140°  F.  This  explains  the  well  known  fact,  on  which  the 
graduation  of  the  thermometer  depends, — that  the  temperature  of 
melting  ice  or  snow  never  exceeds  32°  F.  All  the  caloric  which  is 
added  becomes  insensible,  till  the  liquefaction  is  complete. 

The  loss  of  sensible  caloric  which  attends  liquefaction  seems  essen- 
tially necessary  to  the  change,  and  for  that  reason  is  frequently  called 
the  caloric  of  fluidity.  The  actual  quantity  of  caloric  required  for  this 
purpose  varies  with  the  substance,  as  is  proved  by  the  following  results 
obtained  by  Irvine.  The  degrees  indicate  the  extent  to  which  an  equal 
weight  of  each  material  may  be  heated  by  the  caloric  of  fluidity  which 
is  proper  to  it. 

Caloric  of  fluidity* 

Sulphur 143.68°  F. 

Spermaceti  .....  145 

Lead  162 

Beeswax 175 

Zinc  493 

Tin  500 

Bismuth 550 

All  the  bodies  enumerated  in  this  table,  require,  it  may  be  observed, 
more  caloric  to  bring  them  into  a  fluid  state  than  is  sufficient  to  con- 
vert ice  into  water,  for  which  140°  are  sufficient. 

Other  examples  of  the  absorption  of  caloric  during  the  liquefaction 
of  bodies,  are  furnished  by  the  mixture  of  snow  and  nitric  acid,  or  of 
snow  and  common  salt,  both  of  which,  in  common  language,  produce 
intense  cold.*  Crystallized  muriate  of  lime,  mixed  with  snow,  in  the 
proportion  of  three  parts  of  the  former,  to  two  of  the  latter,  causes  the 
thermometer  to  sink  to  50°.  Most  neutral  salts  also,  during  solution 
in  water,  absorb  much  caloric  ;  and  the  cold  thus  generated,  is  so  in- 
tense as  to  freeze  water  and  even  to  congeal  mercury.  The  congela- 
tion of  water  may  be  easily  affected  on  a  summer's  day,  by  a  mixture 
of  five  parts  of  muriate  of  ammonia,  five  of  nitrate  of  potassa,  eight  of 
sulphate  of  soda,  and  sixteen  of  water. 

For  further  particulars  concerning  the  frigorific  mixtures,  the  reader 
is  referred  to— Walker's  Paper  in  the  Phil.  Trans,  for  1801.  Walker  on 
the  artificial  Production  of  Cold,  Phil.  Mag.  and  Ann.  iii.  401.  Pepys 
and  Allen  s  Account  of  Experiments  on  the  production  of  Cold,  in  one  of 
which  Jifty-six  pounds  of  mercury  were  frozen  into  a  solid  mass.  Tilloch's 
Phil.  Mag.  iii.  76.  A  convenient  apparatus  for  freezing  mercury  is  de- 
scribed by  Dr.  Henry,  in  the  2d  volume  of  his  Chemistry.  Parkcs'  Es- 
say on  Temperature. 

2.  Liquids  in  becoming  solid,  evolve  or  give  out  caloric,  or  in  common 
language,  produce  heat. 

Water,  if  covered  with  a  thin  stratum  of  oil,  and  kept  perfectly  free 
from  agitation,  may  be  cooled  down  more  than  20  degrees  below  32C  ; 

*  The  Peasants  on  the  Baltic  say,  thai  nothing  tends  so  effectually  towards 
the  freezing  of  the  sea  as  a  fall  of  snow  into  the  salt  water.  The  effects  of  a 
snow  storm  are  thus  described  :  "  The  water  becomes  turbid,  like  milk  turn- 
ing to  curd,  pieces  of  ice  soon  made  their  appearance  and  were  heard  rattling 
against  the  prow  and  sides  of  the  vessel."  Dr.  E.  D.  Clarke's  Travels,'}']. 
201,  242. 


4  EFFECTS    OF   CALORIC. 

but  on  shaking  it,  or  dropping  into  it  a  small  fragment  of  ice,  it  imme- 
diately congeals,  and  the  temperature  rises  to  32°. — Madden.  Phil. 
Trans.  1788. 

If  we  dissolve  sulphate  of  soda  in  water,  in  the  proportion  of  one 
part  to  five,  and  surround  the  solution  by  a  freezing  mixture,  it  cools 
gradually  down  to  31°.  The  salt  at  this  point  begins  to  be  deposited, 
and  stops  the  cooling  entirely.  This  evolution  of  caloric,  during  the 
separation  of  a  salt,  is  exactly  the  reverse  of  what  happens  during  its 
solution. — Blagdcn. 

To  a  saturated  solution  of  sulphate  of  potassa  or  sulphate  of  magne- 
sia in  water,  add  an  equal  measure  of  alcohol.  The  alcohol,  attracting 
the  water  more  strongly  than  the  salt  does,  precipitates  the  salt,  and 
considerable  heat  is  produced. 

These  phenomena  are  all  easily  explained  by  Dr.  Black's  doctrine 
of  latent  heat.  According  to  this  doctrine,  caloric  in  causing  fluidity 
loses  its  property  of  acting  on  the  thermometer,  in  consequence  of 
combining  chemically  with  the  solid  substance,  and  liquefaction  results 
because  the  compound  so  formed  does  not  possess  that  degree  of  cohe- 
sive attraction  on  which  solidity  depends.  When  a  liquid  is  cooled  to 
a  certain  point,  it  parts  with  its  caloric  of  fluidity,  heat  is  set  free,  or 
becomes  sensible,  and  the  cohesion  natural  to  the  solid  is  restored. 

VAPORIZATION. 

This  effect  of  caloric  is  conveniently  studied  under  two  heads — Ebul- 
lition and  Evaporation.  In  the  first,  the  production  of  vapour  is  so  rap- 
id that  its  escape  gives  rise  to  a  visible  commotion  in  the  liquid :  in 
the  second,  it  passes  off  quietly  and  insensibly. 

Ebullition.  The  temperature  at  which  vapour  rises  with  sufficient 
freedom  for  causing  the  phenomena  of  ebullition,  is  called  the  boiling 
point.  The  heat  requisite  for  this  effect  varies  with  the  nature  of  the 
fluid.  Thus,  sulphuric  ether  boils  at  96°  F.  alcohol  at  173J,  and  pure 
water  at  212°  ;  while  oil  of  turpentine  must  be  raised  to  316°,  and 
mercury  to  68(P  before  either  exhibits  marks  of  ebullition.  The  boil- 
ing point  of  the  same  liquid  is  constant,  so  long  as  the  necessary  con- 
ditions are  preserved  ;  but  it  is  liable  to  be  affected  by  several  circum- 
stances. The  nature  of  the  vessel  has  some  influence  upon  it.  Thus, 
Gay  Lussac  observed  that  pure  water  boils  precisely  at  212°  in  a  met- 
allic vessel,  and  at  214°  in  one  of  glass.  It  is  likewise  affected  by  the 
presence  of  foreign  particles.  The  same  accurate  experimenter  found, 
that  when  a  few  iron  filings  are  thrown  into  water  boiling  in  a  glass 
vessel,  its  temperature  quickly  falls  from  214  to  212°,  and  remains 
stationary  at  the  last  point. 

But  the  circumstance  which  has  the  greatest  influence  on  the  boil- 
ing point  of  fluids  is  the  variation  of  atmospheric  pressure.  In  refer- 
ence to  this  subject  the  following  propositions  may  be  stated. 

1.  When  atmospheric  pressure  is  diminished,  fluids  boil  at  a  lower  tem- 
perature than  under  the  ordinary  pressure.  Thus  water  which  has  been 
removed  from  the  fire,  and  has  ceased  to  boil,  has  its  ebullition  renew- 
ed, when  it  is  placed  under  a  receiver,  the  air  of  which  is  quickly  ex- 
hausted by  an  air  pump.  Alcohol  and  ether,  confined  under  an  ex- 
hausted receiver,  boil  violently  at  the  temperature  of  the  atmosphere. 
In  general,  liquids  boil,  in  vacuo,  with  about  124°  less  of  heat  than  are 
required  under  a  mean  pressure  of  the  atmosphere.  [Black's  Lectures, 
i.  151.]  Water  therefore  in  a  vacuum  must  boil  at  88°  and  alcohol  at 
49°  F. 


EFFECTS    OF   CALORIC.  55 

The  influence  of  a  diminished  pressure  in  causing  ebullition  to  take 
place  at  a  lower  temperature,  may  also  be  shown  as  follows  : 

Exp.  Fill  a  barometer  tube  with  mercury  and  invert  it  in  a  basin  of 
the  same  fluid  ;  then  pass  up  a  small  quantity  of  ether  by  means  of  a 
half  ounce  phial.  The  ether  upon  reaching  the  torricellian  vacuum 
immediately  springs  into  vapour  and  forces  the  mercury  down  the  tube. 
If  the  tube  is  inclined,  the  ebullition  ceases. 

Exp.  Place  over  a  lamp  a  Florence  flask,  about  three-fourths  filled 
with  water  ;  let  it  boil  briskly  during  a  few  minutes  ;  and  immediate- 
ly on  removing  it  from  the  lamp,  cork  it  tightly,  and  suddenly  invert 
it.  The  water  will  now  cease  to  boil :  but  on  cooling  the  convex  part 
of  the  flask,  by  a  stream  of  cold  water,  the  boiling  will  be  renewed. 
Applying  boiling  water  to  the  same  part  of  the  flask,  the  water  will 
again  cease  to  boil.  This  renewal  of  the  ebullition  by  the  application 
of  cold,  (an  apparent  paradox,)  is  owing  to  the  formation  of  an  imper- 
fect vacuum  over  the  hot  water,  by  the  condensation  of  steam  ;  and 
the  suspension  of  boiling,  on  reapplying  the  heat  to  the  renewed  pres- 
sure on  the  surface  of  the  hot  water,  occasioned  by  the  formation  of 
fresh  steam. 

The  same  fact  is  illustrated  by  the  common  pulse  glass,  in  which 
the  fluid  is  made  to  boil  by  the  mere  heat  of  the  hand. 

2.  When,  atmospheric  pressure,  is  increased,  fluids  require  a  higher  temper- 
ature to  produce  their  ebullition. 

Water  cannot  be  heated  under  common  circumstances  beyond  212°, 
because  it  then  acquires  such  an  expansive  force  as  enables  it  to  over- 
come the  atmospheric  pressure,  and  fly  off  in  the  form  of  vapour.  But 
if  subjected  to  sufficient  pressure,  it  may  be  heated  to  any  extent  with- 
out boiling.  This  is  best  done  by  heating  water  while  confined,  in  a 
strong  copper  vessel,  called  Papin's  Digester.  In  this  apparatus,  on 
the  application  of  heat,  a  large  quantity  of  vapour  collects  above  the 
water,  which  checks  the  ebullition  by  the  pressure  it  exerts  upon  the 
surface  of  the  liquid.  There  is  no  limit  to  the  degree  to  which  wa- 
ter may  be  heated  in  this  way,  provided  the  vessel  is  strong  enough  to 
confine  the  vapour  ;  but  the  expansive  force  of  steam  under  these  cir- 
cumstances is  so  enormous  as  to  overcome  the  greatest  resistance. 

An  apparatus  for  exhibiting  the  same  fact,  has  been  contrived  by  Dr. 
Marcet,  of  which  a  figure  and  description  will  be  found  in  Webster  s 
Brande  and  Henry's  Chcm.  i.  126. 

It  should  be  observed,  that  during  the  conversion  of  a  liquid  into 
vapour,  caloric  is  absorbed.  This  is  proved  by  the  well  known  fact, 
that  the  temperature  of  steam  is  precisely  the  same  as  that  of  boiling 
water  from  which  it  rises,  so  tjiat  all  the  caloric  which  enters  into  the 
liquid  is  solely  employed  in  converting  a  portion  of  it  into  vapour, 
without  affecting  the  temperature  of  either  in  the  slightest  degree,  pro- 
vided the  latter  is  permitted  to  escape  with  freedom.  On  the  other 
hand,  when  this  vapour  is  condensed  into  water,  the  caloric  which  was 
latent,  according  to  the  explanation  of  Dr.  Black,  becomes  free.  The 
exact  amount  of  caloric  rendered  latent  by  vaporization,  may  therefore 
be  ascertained  by  condensing  the  vapour  in  cold  water  and  observing 
the  rise  of  temperature  occasioned  by  it.  From  the  experiments  of 
Dr.  Black  and  Mr.  Watt,  conducted  on  this  principle,  it  appears  that 
steam  of  212°,  gives  out  as  much  caloric  as  would  raise  the  tempera- 
ture of  an  equal  weight  of  water  by  950  degrees,  all  of  which  had  pre- 
viously existed  in  the  vapour  without  being  sensible  to  a  thermometer. 
The  latent  heat  of  the  vapours  of  different  liquids  has  been  investi- 


56  EFFECTS   OF   CALORIC. 

gated  by  Dr.  Ure,  and  by  M.  Despretz.     From  the  results,  Dr.  Ure  has 
constructed  a  table.     [See  his  Dictionary  of  Chemistry.'} 

The  only  fluid,  the  vapour  of  which  can  be  converted  to  any  particu- 
lar use,  is  water.  Owing  to  the  heat  which  it  gives  out  when  conden- 
sed into  steam,  it  is  often  used  for  heating  large  quantities  of  water. 
It  is  also  employed  for  heating  rooms  and  for  carrying  on  different 
chemical  processes,  in  which  too  great  heat  would  be  injurious,  as  in 
assisting  fermentation  and  in  drying  substances  gradually,  and  with- 
out the  risk  of  burning. 

In  consequence  of  the  great  elasticity  of  steam,  it  is  employed  as 
a  moving  power  in  the  steam-engine.  The  construction  of  this  ma- 
chine depends  on  two  properties  of  steam,  namely,  the  expansive 
force  communicated  to  it  by  caloric,  and  its  ready  conversion  into 
water  by  cold.  The  effect  of  both  these  properties  is  well  shown  by 
a  little  instrument  devised  by  Dr.  Wollaston.  It  consists  of  a  cylin- 
drical glass  tube,  six  inches  long,  nearly  an  inch  wide,  and  blown 
out  into  a  spherical  enlargement  at  one  end.  A  piston  is  accurately 
fitted  to  the  cylinder,  so  as  to  move  up  and  down  the  tube  with  free- 
dom. When  the  piston  is  at  the  bottom  of  the  tube,  it  is  forced  up 
by  causing  a  portion  of  the  water,  previously  placed  in  the  ball,  to  boil 
by  means  of  a  spirit-lamp.  On  dipping  the  ball  into  cold  water,  the 
steam  which  occupies  the  cylinder  is  suddenly  condensed,  and  the  pis- 
ton forced  down  by  the  pressure  of  the  air  above  it.  By  the  alternate 
application  of  heat  and  cold,  the  same  movements  are  reproduced,  and 
may  be  repeated  for  any  length  of  time. 

The  moving  power  of  the  steam-engine  is  the  same  as  in  this  ap- 
paratus. The  only  essential  difference  between  them  is  in  the  mode 
of  condensing  the  steam.  In  the  steam-engine,  the  steam  is  con- 
densed in  a  separate  vessel,  called  the  condenser,  where  there  is  a  re- 
gular supply  of  cold  water  for  the  purpose.  By  this  contrivance, 
which  constitutes  the  great  improvement  of  Watt,  the  temperature  of 
the  cylinder  never  falls  below  212°. — Turner. 

REFERENCES.  For  a  table  of  the  boiling  points  of  the  most  important 
liquids,  see  Ure\t  Diet,  of  Client,  and  L.  U.  K.  art.  Heat,  50.  Gay  Lussar. 
Muncke  and  Biot,  on  the  fixedness  of  the  boiling  point  of  Fluids — Ann.  of 
Phil.  xii.  129.  Lardner^s  Popular  Lectures  on  the  Steam- Engine,  and 
Professor  Remcick's  Treatise  on  the  same  subject. 

Evaporation.  Evaporation  as  well  as  ebullition  consists  in  the  for- 
mation of  vapour,  and  the  only  assignable  difference  between  them  is, 
that  the  one  takes  place  quietly,  the  other  with  the  appearance  of 
boiling.  Evaporation  takes  place  at  common  temperatures,  as  may 
be  proved  by  exposing  water  in  a  shallow  vessel  to  the  air  for  a  few 
days,  when  it  will  gradually  diminish,  and  at  last  disappear  entirely. 
Most  fluids,  if  not  all  of  them,  are  susceptible  of  this  gradual  dissi- 
pation ;  and  it  may  also  be  observed  in  some  solids,  as  for  example, 
in  camphor.  Evaporation  is  much  more  rapid  in  some  fluids  than  in 
others,  and  it  is  always  found  that  those  liquids,  whose  boiling  point 
is  the  lowest,  evaporate  with  the  greatest  rapidity.  Thus  alcohol, 
which  boils  at  a  lower  temperature  than  water,  evaporates  also  more 
freely  ;  and  ether,  whose  point  of  ebullition  is  lower  than  that  of 
alcohol  evaporates  with  still  greater  rapidity. 

The  chief  circumstances  that  influence  the  process  of  evaporation 
are  extent  of  surface,  and  the  state  of  the  air  as  to  temperature,  dry- 
ness,  stillness,  and  density. 


EFFECTS   OF   CALORIC.  57 

As  a  large  quantity  of  caloric  passes  from  a  sensible  to  an  insensi- 
ble state  during  the  formation  of  vapour,  it  follows  that  cold  should 
be  generated  by  evaporation.  A  very  simple  experiment  will  prove 
it.  If  a  few  drops  of  ether  be  allowed  to  fall  upon  the  hand,  a  strong 
sensation  of  cold  will  be  excited  during  the  evaporation  ;  or  if  the 
bulb  of  a  thermometer,  covered  with  lint,  be  moistened  with  ether, 
the  production  of  cold  will  be  marked  by  the  descent  of  the  mercu- 
ry.*1 But  to  appreciate  the  degree  of  cold  which  may  be  produced  by 
evaporation,  it  is  necessary  to  render  it  very  rapid  and  abundant  by 
artificial  processes  ;  and  the  best  means  of  doing  so,  is  by  removing 
pressure  from  the  surface  of  volatile  liquids.  Water  placed  under 
the  exhausted  receiver  of  an  air  pump,  evaporates  with  great  rapidi- 
ty, and  so  much  cold  is  generated  as  would  freeze  the  water,  did  the 
vapour  continue  to  rise  for  some  time  with  the  same  velocity.  But 
the  vapour  itself  soon  fills  the  vacuum,  and  retards  the  evaporation 
by  pressing  upon  the  surface  of  the  water,  t  This  difficulty  may  be 
avoided  by  putting  under  the  receiver  a  substance,  such  as  sulphuric 
acid,  which  has  the  property  of  absorbing  watery  vapour,  and  conse- 
quently of  removing  it  as  quickly  as  it  is  formed.  Such  is  the  prin- 
ciple of  Mr.  Leslie's  method  for  freezing  water  by  its  own  evapora- 
tion.— Edinburgh  Encyclopedia,  art.  Cold.  See  also  Dr.  Cullen  on  the 
Cold  produced  by  Evaporation,  Edinburgh  Physical  and  Literary  Es- 
says, ii.  159. 

The  action  of  the  Cryophorus,  an  ingenious  contrivance  of  Dr. 
Wollaston,  depends  on  the  same  principle.  It  consists  of  two  glass 
balls,  perfectly  free  from  air,  and  joined  together  by  a  tube.  One 
of  the  balls  contains  a  portion  of  distilled  water,  while  the  other 
parts  of  the  instrument,  which  appear  empty,  are  full  of  aqueous  va- 
pour, which  checks  the  evaporation  from  the  water  by  the  pressure  it 
exerts  upon  its  surface.  But  when  the  empty  ball  is  plunged  into  a 
freezing  mixture,  all  the  vapour  within  it  is  condensed;  evaporation 
commences  from  the  surface  of  the  water  in  the  other  ball,  and  it  is 
frozen  in  two  or  three  minutes  by  the  cold  thus  produced. — Phil. 
Trans.  1813. 


*  The  production  of  cold  during  evaporation,  is  by  no  means  confined  to 
the  more  volatile  liquids.  Koempfer  states,  that  on  the  borders  of  the  Persian 
Gulf  the  winds  are  so  scorching,  that  travellers  are  suddenly  suffocated,  un- 
less they  cover  their  heads  with  a  wot  cloth  ;  but  if  this  be  too  wet,  they  im- 
mediately feel  an  intolerable  cold,  which  would  become  fatal  to  them  if  the 
moisture  were  not  speedily  dissipated  by  the  heat.  The  cold,  which  is  pro- 
duced by  the  act  of  evaporation,  ceases  as  soon  as  that  is  finished,  by  the 
cloth  becoming  dry. —  Watson's  Chem.  Essays,  iii.  126.  Wet  clothes  also 
are  injurious,  because  the  evaporation  produces  cold  on  the  surface  and  thus 
<  onstricts  the  extreme  vessels. 

f  [n  Glasgow  and  the  neighborhood,  soda  and  alum  leys  are  brought  to  the 
requisite  degree  of  concentration,  by  passing  over  their  surface  a  brisk  current 
of  air  which  has  previously  passed  through  a  fire  ;  so  that  the  flame  of  the  fire 
plays  over  the  surface  of  the  evaporating  liquor.  And  this  process  has  been 
found  more  convenient  and  economical,  than  the  method  of  evaporating  liquid* 
by  applying  heat  to  the  bottom  of  vessel?  containing  them. —  Thomson's  Out- 
lines of  Heat,  #r.  243. 


58  EFFECTS   OF   CALORIC. 

Liquids  which  evaporate  more  rapidly  than  water,  cause  a  still 
greater  reduction  of  temperature.  The  cold  produced  by  the  evapo- 
ration of  ether  in  the  vacuum  of  the  air-pump,  is  so  intense  as  under 
favorable  circumstances  to  freeze  mercury.  Advantage  has  also  been 
taken  of  this  circumstance  in  Mr.  Howard's  plan  for  refining  sugar, 
and  in  plans  for  preparing  pharmaceutical  extracts  in  vacua. — Repcrtc:y 
of  Arts,  2d  Ser.  xxiii.  4*  xxv. 

Concerning  the  cause  of  evaporation  a  difference  of  opinion  exists 
among  chemists.  It  was  at  one  time  supposed  to  be  owing  to  a  chem- 
ical attraction  between  the  air  and  water.  But  Mr.  Dalton  has  shown, 
that  caloric  is  the  true  and  the  only  cause  of  the  formation  of  vapour. 
As  our  limits  do  not  permit  us  to  enter  into  these  discussions,  we  shall 
refer  the  reader  to — Turner's  Chemistry.  Henry's  Chem.  Dalton,  in 
Manchester  Memoirs,  v.  Ure,  in  Phil.  Trans.  1818.  Biot  Traite  de 
Pkys.  1.  Faraday  on  ike  existence  of  a  limit  to  Vaporization,  PhiL 
Trans.  1826. 

The  presence  of  watery  vapour  in  the  atmosphere,  is  owing  to 
evaporation  which  takes  place  from  the  water  on  the  surface  of  the 
earth.  As  this  evaporation  goes  on  to  a  certain  extent,  even  at  low 
temperatures,  it  is  probable  that  vapour  is  always  present  in  the  air, 
though  its  quantity  is  subject  to  great  variation,  in  consequence  of 
the  changes  of  temperature  to  which  the  air  is  constantly  subjected. 
But  even  when  the  temperature  is  the  same,  the  quantity  of  vapour 
is  still  found  to  vary ;  for  the  air  is  not  always  in  a  state  of  satura- 
tion. At  one  time  it  is  excessively  dry  ;  at  another  it  is  fully  satu- 
rated ;  and  at  other  times  it  varies  between  these  extremes.  Instru- 
ments have  been  constructed  to  determine  this  variable  condition  of 
the  atmosphere  as  to  saturation,  which  are  called  Hygrometers.  These 
consist  for  the  most  part  of  some  substance,  such  as  human  hair,  or  a 
fine  slip  of  whale  bone,  which  is  elongated  by  a  rnoist  atmosphere,  and 
shortened  by  a  dry  one.  The  extreme  points  are  attained  by  placing 
it,  first  in  air  artificially  dried,  and  then  in  air  rendered  as  humid  as 
possible.  The  degree  of  expansion  or  contraction  is  rendered  more 
sensible  by  connecting  it  with  an  axis,  which  moves  a  circular  index, 
like  the  finger  of  a  clock.  Mr.  Leslie,  by  a  slight  modification  of  his 
differential  thermometer,  makes  it  serve  the  purpose  of  an  hygrome- 
ter :  for  if  one  of  the  balls  be  covered  with  silk,  and  then  moistened 
with  water,  the  rate  of  evaporation  will  be  shown  by  the  degree  of 
cold  produced,  as  indicated  by  the  descent  of  the  liquid  in  the  oppo- 
site leg  of  the  instrument.  The  drier  the  air,  the  quicker  will  be  the 
evapoiation,  and  the  greater  the  effect  in  moving  the  liquid  within  the 
instrument. — Henry,  i.  280. 

But  the  most  perfect  instrument  of  this  kind,  is  that  invented  by 
Mr.  Daniell,  for  a  particular  description  of  which  the  reader  is  re- 
ferred to  DaniclVs  Meteorological  Essays — or  to  the  Library  of  Useful 
Knowledge,  art.  Pyrometer  and  Thermometer,  where  several  modifica- 
tions of  the  tfygrtfmtttr  are  also  described.  For  information  on  the 
subject  of  Hygrometers,  sec  also  Prof.  Forbes'  Jteport  on  Meteorology, 
made  to  the  Brit.  Ass.  in  1832.  I  should  also  mention  that  Mr.  A. 
Hayes  has  described  a  dew-point  Hygrometer  in — Siltimfai's  Jour- 
nal, xvii.  351. 


SPECIFIC    CALORIC.  59 

SECTION  V. 

SPECIFIC    CALORIC. 

Equal  weights  of  the  same  body  at  the  same,  temperature,  contain 
the  same  quantity  of  caloric.  But  equal  weights  of  different  bodies 
at  the  same  temperature,  contain  unequal  quantities  of  caloric.  Thus 
if  we  add  a  pint  of  water  at  100J  F.  to  a  pint  of  the  same  liquid  at 
50a,  the  mixture  will  have  a  temperature  of  75°,  or  the  mean  between 
the  two  ;  that  is,  the  25°  which  the  hot  water  has  lost,  has  been  just 
sufficient  to  raise  the  cold  by  as  many  degrees.  But  if  one  pound  of 
mercury  at  185°  F.  is  mixed  with  a  pound  of  water  at  40°,  the  mix- 
ture will  have  a  temperature  of  45°  only  ;  or  if  the  experiment  be  re- 
versed by  having  the  water  at  185°  and  the  mercury  at  40°,  the  mix- 
ture will  have  a  temperature  of  180°.  In  the  first  case,  140  degrees 
lost  by  the  mercury  served  to  heat  the  water  by  five  degrees,  and  in 
the  second,  five  degrees  lost  by  the  water  sufficed  to  raise  the  temper- 
ature of  the  mercury  by  140°.  It  hence  appears  that  28  times  more 
caloric  is  required  to  raise  the  temperature  of  water  through  one  or 
more  degrees,  than  for  heating  an  equal  weight  of  mercury  to  the 
same  extent. 

By  mixing  water  with  various  other  substances  it  has  been  found  that 
it  requires  different  quantities  of  caloric  to  heat  them  equally.  Thus 
on  the  addition  of  warm  water  to  a  jar  containing  a  pound  of  water  at 
50°,  the  temperature  will  rise,  say  10° ;  on  adding  a  similar  quantity 
of  warm  water  to  another  jar  containing  a  pound  of  spermaceti  oil, 
it  will  rise  20°  ;  and  the  same  addition  to  a  jar  containing  a  pound  of 
powdered  glass  will  cause  a  rise  of  50°. 

Here  then  it  will  be  observed  that  equal  quantities  of  caloric  added 
to  water,  oil  and  glass,  have  raised  the  temperature  of  the  first  10,  of 
the  second  20,  and  of  the  third  50  degrees.  Now  it  is  clear  that  if  we 
wished  to  raise  them  all  to  the  same  temperature,  say  50°,  we  must 
add  twice  and  a  half  as  much  to  the  oil,  and  five  times  as  much  to  the 
water.  The  quantities  of  caloric  which  they  are  capable  of  receiving, 
are  therefore  as  glass  10,  oil  20,  water  50  ;  or  taking  water  as  the 
standard,  and  calling  it  1000,  they  are  water  1000,  oil  500,  glass  200. 

The  term  employed,  to  designate  this  remarkable  difference,  by  Dr. 
Black,  who  first  observed  it,  was  capacity  for  caloric.  But  as  this  term 
is  apt  to  lead  to  erroneous  impressions  concerning  the  cause  of  this 
difference,  that  of  specific  caloric  has  been  substituted  for  it,  and  is  now 
generally  employed. 

When  substances  can  be  mixed  together,  as  in  the  instances  above 
mentioned,  their  specific  caloric  can  be  determined,  by  ascertaining 
the  relative  quantities  of  caloric  which  is  requisite  for  heating  them  by 
an  equal  number  of  degrees.  Water  is  commonly  employed  as  one 
of  the  substances,  and  the  specific  caloric  of  other  bodies  is  usually 
compared  with  that  of  water. 

In  some  cases,  however,  the  bodies  under  examination  cannot  be  in- 
timately mixed.  When  the  specific  heat  of  a  solid  mass  of  metal  is  to 
be  examined,  it  may  be  heated  throughout  to  a  certain  degree,  and  then 
surrounded  by  water,  at  32°,  observing  the  increase  of  temperature, 
which  is  gained  by  the  water,  and  calculating  the  specific  heat  as  be- 
fore. This  was  the  method  of  Wilcke,  of  Stockholm. — [Thomson's 
Chem.  i.  100.]  Lavoisier  and  La  Place  substituted  ice  for  water, 
placing,  by  means  of  an  apparatus  called  the  Calorimeter,  the  heated 


60  SPECIFIC    CALORIC. 

body  in  the  centre  of  a  quantity  of  ice,  and  determining  the  caloric 
evolved,  by  the  quantity  of  ice  melted  in  each  instance. — Lavoisier's 
Elements. 

It  has  been  ascertained  by  Petit  and  Dulong,  who  have  recently  in- 
vestigated this  subject,  that  the  specific  heats  of  bodies  are  greater  at 
high  than  at  low  temperatures.  They  have  also  deduced  from  their 
researches  the  law,  that  the  atoms  of  all  simple  bodies  have  precisely  the 
same  specific  heat. — [Ann.  of  Phil.  v.  13.]  This,  however,  is  to  be 
considered  at  present,  merely  in  the  light  of  an  ingenious  speculation, 
derived  from  a  train  of  reasoning,  a  defect  in  any  part  of  which  must 
be  fatal  to  the  conclusions. — See  Henry,  i.  160. — Dalton's  New  Syst.  ii. 
280.  Also,  Professor  Bache's  Strictures  on  the  Table  of  Petit  and  Du- 
long—Jour,  of  the  Acad.  of  Nat.  Scien.  Phil.  Jan.  1829. 

The  determination  of  the  specific  heat  of  gases  has  successively  en- 
gaged the  attention  of  some  of  the  most  profound  and  ingenious 
chemical  philosophers.  Among  the  most  valuable  observations  on 
this  subject,  are  those  of  Delaroche  and  Berard,  De  La  Rive  and  F. 
Marcet.  In  the  experiments  of  the  two  latter  philosophers  which  are 
the  most  recent,  they  appear  to  have  avoided  sources  of  fallacy  which 
were  not  provided  against  by  those  who  preceded  them  in  these  in- 
vestigations. From  a  review  of  their  experiments,  they  consider  the 
following  conclusions  as  legitimately  deducible. 

1.  That  under   the  same  pressure,   and  with  equal  and  constant 
volumes,  (the  elasticity  alone  varying,)  all  gases  have  the  same  spe- 
cific heat. 

2.  That,  all  other  circumstances  remaining  the  same,  the  specific 
heat  diminishes  at  the  same  time  as  the  pressure,  and  equally  for  all 
gases,  according  to  a  progression  but  little  convergent,  and  in  a  much 
less  ratio  than  that  of  the  pressures. 

3.  That  each  gas  has  a  different  power  of  conducting  heat. — Henry's 
Chem.  i.  163. 

REFERENCES.  For  tables  of  the  Specific  Htats  of  some  Gases,  see  Library 
of  Useful  Knowledge,  Art.  Heat,  or  Thomson's  Outline  of  Heat,  fyc.  71. 
Delaroche  and  Berard  on  the  Specific  Heat  of  Gases,  Ann.  of  Phil.  ii. 
Herepath  on  the  causes  of  Heat  in  Gases,  Ann.  Phil.  xvii.  Same  author's 
Tables  of  Temperature,  and  replies  to  him,  Ann.  of  Phil.  xvii.  &  xviii. 
Meikle  on  the  Specific  Heat  of  Air.  Edin.  New  Phil.  Jour.  ii.  328. 

SECTION  VI. 

SOURCES    OP    CALORIC. 

The  sources  of  caloric  may  be  reduced  to  six,  viz. 

1.  THE  SUN,  4.  MIXTURE, 

2.  FRICTION,  5.  ELECTRICITY, 

3.  PERCUSSION,  6.  COIUBUSTIQN. 

The  Sun.  The  heat  produced  by  the  sun  is  found  to  differ  according 
to  the  surface  exposed,  and  the  colour  of  the  surface.  Franklin  found 
that  when  pieces  of  cloth  of  various  colours  were  exposed  upon  snow 
to  the  light  of  the  sun,  they  sunk  deeper,  and  consequently  acquired 
heat,  in  proportion  to  the  darkness  of  their  colour.  This  experiment 
was  repeated  with  more  precision  by  Sir  H.  Davy,  with  similar  results. 

The  temperature  produced  by  the  direct  action  of  the  sun's  rays  sel- 
dom exceeds  120°  ;  a  higher  temperature  however,  may  be  produced 


SOURCES    OF    CALORIC.  61 

if  we  prevent  the  heat  communicated  from  being  carried  off  to  sur- 
rounding bodies. 

But  when  the  sun's  rays  are  concentrated  by  means  of  a  burning 
lens,  intense  heat  is  produced,  provided  they  are  directed  upon  some 
body  capable  of  absorbing  and  retaining  them.  Some  lenses  have 
been  constructed  of  extraordinary  power,  and  among  them  may  be 
mentioned  those  of  Tschirnhausen  and  M.  de  Trudaine,  by  which 
many  of  the  most  refractory  substances  were  readily  fused.  [For  a 
description  of  these  and  other  powerful  lenses,  see  Cliaptal's  Chem. 
app.  to  the  Arts,  and  Parkes'  Chcm.  Essays.]  According  to  Count 
Buffon,  however,  the  only  way  by  which  the  sun's  rays  can  be 
made  to  produce  an  intense  heat  at  a  great  distance,  is  by  the  com- 
bination of  a  considerable  number  of  plain  mirrors,  so  disposed  'as  to 
throw  numerous  images  of  the  sun  upon  the  same  spot.v  By  an  in- 
strument constructed  upon  this  principle  he  was  enabled  to  melt  the 
metals  and  metallic  minerals  at  the  distance  of  forty  feet,  and  to  kin- 
dle wood  when  at  the  distance  of  210  feet. — Parked  Chem.  Essays. 

2.  Friction.     Fires  are  often  kindled  by  rubbing  pieces  of  dry  wood 
smartly  against  one  another.     So  also  when  parts  of  heavy  machine- 
ry rub  against  one  another,  the  heat  excited,  if  the  parts  in  contact 
are  not  well  greased,  is  sufficient  for  kindling  wood.     The  axle-tree 
of  carriages  has  been  burned  from  this  cause,  and  the  sides  of  ships 
are  said  to  have  takSn  fire  by  the  rapid  descent  of  the  cable. — [Parry's 
2d    Voyage,  N.  Y.  Ed.  212.]     Count  Rumford  observed,   that  in  the 
boring  of  cannon,  by  the  friction  of  the  borer,  a  very  large  quantity 
of  caloric  is  rendered  sensible.     To  ascertain  its  quantity,  he  fixed  a 
solid  cylinder  of  brass  in  a  trough  filled  with  water,  and  having  adapt- 
ed the  borer  to  it,  connected  with  the  machinery  by  which  it  is  turn- 
ed, it  was  made  to  revolve  in  the  usual  manner,  at  the  rate  of  32  times 
in  a  minute.     Heat  was  soon  excited,   and  of  course  raised  the  tem- 
perature of  the  metal,  and  of  the  surrounding  water.     In  an  hour  the 
temperature  had  risen  from  60  to  107°  ;  and  in  two  hours  and  a  half 
the  water  was  brought  to  boil,  the  quantity  of  this  water  being  18  Ibs. ; 
the  apparatus  itself,  which  was  of  course  raised  to  the  same  tempera- 
ture, weighed  15  Ibs. 

From  this  experiment  it  may  be  safely  concluded,  that  the  access  of 
atmospheric  air  is  not  essential  to  the  evolution  of  caloric  ;  an  infer- 
ence confirmed  also  by  the  experiment  of  Pictet — who  constructed  an 
apparatus  by  which  friction  could  be  excited  in  an  exhausted  receiver. 
The  thermometer  rose  higher  than  when  this  friction  was  going  on  in 
open  air.  Rumford1  s  Essays — Pictet' s  Essay  on  Fire. 

It  was  hence  concluded  by  these  philosophers  that  caloric  was  not  a 
material  substance,  but  a  kind  of  motion.  The  same  opinion  was 
adopted  by  Sir  H.  Davy.  But  although  these  facts  present  a  difficulty 
in  the  adoption  of  the  hypothesis  that  caloric  is  material,  the  other 
phenomena  can  be  more  satisfactorily  explained  upon  the  latter  sup- 
position, and  hence  it  is  quite  generally  adopted  by  the  chemists  of  the 
day. — See  references  under  the  first  Section  of  this  Chapter. 

3.  Percussion.     The   heat   excited  by  percussion  is  equal,   and  in 
many  cases  superior,  to  that  evolved  by  friction.     When  a  piece  of  iron 
is  smartly  and  quickly  struck  with  a  hammer,  it  becomes  red  hot ;  and 
another  familiar  illustration  is  the  production  of  heat  by  the  compres- 
sion ofair  in  the  common  fire-syringe.     No  heat,  however,   has  been 
observed  to  follow  the  percussion  of  liquids,  nor  of  soft  bodies  which 
easily  j'ield  to  the  stroke. 

£ 


62  SOURCES   OF   CALORIC. 

4.  Mixture.     We  have  already  given  some  examples  of  the  effect  of 
mixture  in  producing  heat ;  as  in  the  case  of  the  mixture  of  sulphuric 
acid  and  water,   and  the  mixture  of  sulphuric  acid  with  the  chlorate 
of  potash  and  sugar.     [See  page  23.]     So  also  some  gaseous  bodies, 
which,  when  united  .together,  form  solids,  as  ammoniacal  and  muriatic 
acid  gases,    evolve  a  considerable  degree  of  heat.     Some  times,  how- 
ever, the  temperature  of  the  mixture  is  reduced,  and  the  sensation  of 
cold  produced ;  as  is  remarkably  the  case  in  some  of  the  freezing  mix- 
tures. 

It  may  be  laid  down  as  a  rule,  to  which  there  are  few  exceptions, 
that  when  the  compound  formed  by  the  union  of  two  bodies  is  more 
fluid  or  dense  than  the  mean  fluidity  or  density  of  the  two  bodies  be- 
fore mixture,  then  the  temperature  sinks  ;  but  when  the  fluidity  or  the 
density  of  the  new  compound  is  less  than  that  of  the  two  bodies  be- 
fore mixture,  the  temperature  rises  ;  and  the  rise  is  pretty  nearly  pro- 
portional to  the  difference. — Thomson's  Chem.  i.  143. 

5.  Electricity.     This  will  be  particularly  noticed  in  Chapter  4. 

6.  Combustion.     This  may  be  denned  to  be  the  disengagement  of 
heat  and  light  which  accompany  chemical  action. 

Modern  discoveries  have  shown  the  insufficiency  of  former  theories 
upon  this  subject.  But  in  the  present  state  of  our  knowledge,  we  are 
unable  to  substitute  one  that  is  wholly  free  from  objection  ;  and  we 
are  left  to  the  naked  statement  of  the  fact,  that  combustion  is  the 
general  result  of  the  actions  of  any  substances  which  possess  strong 
chemical  attractions,  or  different  electrical  relations. — Ures  Chem. 
Dictionary. 

I  shall  notice  the  leading  phenomena  of  combustion  under  the  fol- 
lowing heads,  viz. 

1.  The  temperature  necessary  to  inflame  different  bodies. 

2.  The  nature  of  flame. 

3.  The  heat  given  out  by  different  combustibles  in  burning. 

4.  The  causes  which  modify,  promote  or  extinguish  combustion. 

1.  The  temperature  necessary  to  inflame   bodies. — The   temperature 
necessary  for  inflammation,  is  very  different  in  different  bodies.     Thus, 
if  we  heat  phosphorus  to  150°  F.  it  takes  fire ;  but  sulphur  requires  a 
heat  of  500 3  for  its  inflammation. 

The  successive  combustibilities  of  bodies  can  be  shown  as  follows  : 
Exp.  Into  a  long  bottle  with  a  narrow  neck  introduce  a  lighted 
taper,  and  let  it  burn  till  it  is  extinguished.  Carefully  stop  the  bottle 
and  introduce  another  lighted  taper.  It  will  be  extinguished  before  it 
reaches  the  bottom  of  the  neck.  Then  introduce  lighted  sulphur. 
This  will  burn  for  some  time  ;  and  after  its  extinction,  phosphorus  will 
be  as  luminous  as  in  the  air,  and  if  it  be  heated  will  burn  with  a  pale 
yellow  flame. 

The  combustibilities  of  various  gaseous  bodies  are  to  a  certain  ex- 
tent as  the  masses  of  heated  matter  required  to  inflame  them.  Thus, 
an  iron  wire  l-40th  of  an  inch  in  diameter,  heated  to  a  cherry  red, 
will  not  inflame  olefiant  gas,  but  it  will  inflame  hydrogen.  A  wire  of 
l-8th  of  an  inch,  heated  to  the  same  degree,  will  inflame  olefiant  gas. 
But  a  wire  l-500th  of  an  inch,  must  be  heated  to  whiteness  to  inflame 
hydrogen,  though  at  a  low  red  heat  it  will  inflame  bi-phosphuretted  gas. 

2.  Nature  of  flame. — Flame  is  the  rapid  combustion  of  volatilized 
matter,  or  in  other  words,  volatile  combustible  matter  heated  so  highly 


SOURCES    OF   CALORIC.  63 

>  t 

as  to  become  luminous.  Davy  has  asserted  that  the  flame  of  combus- 
tible bodies  must  be  considered  as  the  combustion  of  an  explosive 
mixture  of  inflammable  gas  or  vapour  and  air,  and  that  this  combus- 
tion takes  place  in  the  interior  as  well  as  at  the  surface  of  contact.  A 
simple  experiment,  however,  proves  that  no  combustion  goes  on  in  the 
interior  of  a  flame. 

Exp.  Place  a  piece  of  coin  or  metal  upon  an  earthen  plate  ;  place 
a  small  piece  of  phosphorus  upon  the  coin,  and  surround  the  latter 
with  alcohol.  The  alcohol  may  be  fired  without  setting  fire  to  the 
phosphorus,  which  remains  unaffected  in  the  interior  of  the  flame,  but 
as  soon  as  the  external  air  comes  in  contact  with  it,  combustion  in- 
stantly takes  place. 

The  interior  of  a  flame  consists  of  aqueous  vapour,  which  may  be 
exhibited  by  an  ingenious  apparatus  contrived  by  Mr.  Blackadder. — 
Edin.  New  Phil.  Jour.  i.  224. 

The  light  of  a  flame  may  be  shown  by  the  prism  to  consist  of  sev- 
eral colours.  The  flame  of  a  candle  consists  of  four  portions,  al- 
though these  may  be  considerably  modified  by  various  circumstances. 
A  blue  portion  which  extends  from  the  base  to  about  the  middle  of 
the  flame  ; — an  attenuated  opaline  brush  over  the  whole  exterior 
surface  of  the  blue  part  of  the  flame  ;  a  cone  ot  yellowish  white  light, 
commencing  on  the  inner  surface,  and  at  a  short  distance  from  the 
base  of  the  blue  portion  ;  and  an  interior  cone  of  white  light,  the  base 
of  which  is  above  the  upper  part  of  the  blue  portion. — Edin.  New. 
Phil.  Jtmr.  i.  228. 

Flame  has  electric  polarity  ;  that  of  burning  phosphorus  being  acid, 
is  bent  towards  the  positive  pole,  and  that  of  a  candle  containing  ig- 
nited carbon,  toward  the  negative. — Brande,  Phil.  Trans.  1814,  noticed 
in  Ann.  of  Phil.  iv.  441. 

The  products  of  flame  are  usually  water  and  carbon. 

The  use  of  a  wick  is  to  raise  the  fluid  by  capillary  attraction.  It  is 
not,  however,  an  essential  part  of  the  oil  or  alcoholic  lamp.  Lamps 
without  wicks  have  been  constructed  by  Mr.  Blackadder,  and  are 
supposed  by  him  to  possess  many  advantages. — Ed.  New  Phil.  Jour. 
i.  52. 

The  colour  of  flame  depends  upon  the  presence  of  various  for- 
eign substances,  and  an  attention  to  it  is  of  great  utility  in  many 
analytical  researches.  Thus  the  flame  of  alcohol  is  tinged  with  a 
fine  carmine  red  by  nitrate  of  strontia,  yellow  by  nitrate  of  baryta, 
green  by  nitrate  of  copper,  &c.  This  is  by  some  supposed  to  be 
owing  to  the  reduction  of  the  substances  employed,  to  the  metallic 
state. 

Flame  is  supposed  to  possess  a  very  high  temperature.  By  Sir  H. 
Davy  it  was  estimated  at  7000°  F.  But  there  can  be  no  doubt  that 
the  temperature  varies  with  the  combustible,  and  that  it  is  influenced 
also  by  other  circumstances  ;  and  it  perhaps  never  reaches  the  point 
first  mentioned.  One  of  the  arguments  advanced  by  Davy,  viz.  that  a 
fine  platina  wire  becomes  white  hot  in  a  part  of  the  flame  of  a  spirit 
lamp  where  there  is  no  visible  light,  has  been  weakened  by  the  fact 
since  discovered,  that  the  mere  contact  of  a  jet  of  hydrogen  with 
spongy  platina  causes  the  incandescence  of  the  latter.  The  other 
argument  of  Davy  appears  also  open  to  objection. 

3.  Heat  given  out  by  different  combustibles  in  burning. 

On  this  subject  experiments  have  been  made  by  Lavoisier,  Crawford, 
Dalton,  Rumford  and  Davy.  But  the  results  of  these  experiments  are 


64  SOURCES    OF    CALORIC. 

so  discordant  that  they  can  scarcely  afford  any  correct  guide.  They 
appear  to  agree,  however,  that  of  the  numerous  substances  tried,  hy- 
drogen gives  out  the  most  heat  and  carbonic  oxide  the  least. —  Ure's 
Chem.  Dictionary. 

With  respect  to  the  heat  given  out  by  ordinary  combustibles  used 
as  fuel,  the  experiments  of  Mr.  Bull,  of  Philadelphia,  are  the  most 
satisfactory.  The  following  results  are  extracted  from  his  table, 
in  the  Transactions  of  the  American  Philosophical  Society,  N.  S.  iii.  1. 
Amount  of  heat  given  out  by  various  combustibles — a  cord  of  shell- 
bark  hickory  being  equal  to  100. 

Shell-bark  hickory 100 

White  oak  81 

Hard  maple  ......          60 

White  beech 65 

White  pine 42 

Lehigh  coal  (a  ton  2240  Ibs.)  ...  99 
Lacka waxen  coal  .....  99 
Schuylkill  coal  103 

4.    Causes  ichich  modify,  promote  or  extinguish  combustion. 

Although  the  progress  of  discovery  has  shown  that  the  general- 
ization proposed  by  Lavoisier,  viz.  that  in  all  cases  of  combustion, 
oxygen  combines  with  the  burning  body,  is  not  of  universal  applica- 
tion ;  it  must  be  confessed  that  in  most  cases  the  presence  of  oxygen 
is  essential  to  the  process  of  combustion.  In  ordinary  cases,  the  more 
complete  the  access  of  atmospheric  air  and  the  more  perfect  its  contact 
with  the  combustible,  the  more  perfect  will  be  the  combustion.  It  is 
upon  this  principle  that  most  of  the  modern  improvements  in  the  con- 
struction of  lamps  and  furnaces  depend. 

Upon  the  same  principle  also  the  heat  may  be  greatly  increased, 
by  causing  a  blast  through  a  flame.  For  this  purpose,  a  blow-pipe,, 
to  be  blown  either  by  the  mouth  or  a  pair  of  bellows,  is  used.  The 
form  of  this  instrument  is  not  material ;  and  several  modifications 
of  it  have  been  proposed.  The  principle  upon  which  it  acts,  is  that 
a  constant  supply  of  air  is  brought  to  the  inflammable  matter,  thus 
rendering  the  combustion  more  complete,  and  the  consequent  heat 
greater. 

There  are  other  forms  of  the  blow-pipe,  as  that  in  which  alcohol 
is  employed,  and  the  oxy-hydrogen  blow-pipe,  which  will  be  noticed 
hereafter. 

Flame  being  gaseous  matter  so  highly  heated  as  to  become  lumin- 
ous, will  be  extinguished  by  a  reduction  of  its  temperature.  This  can 
be  effected  by  bringing  near  it  some  metallic  conductor. 

Let  the  smallest  possible  flame  be  made  by  a  single  thread  of  cot- 
ton immersed  in  oil,  it  will  be  found  to  yield  a  flame  of  about  l-30th 
of  an  inch  in  diameter.  Let  a  fine  iron  wire  of  1 -180th  of  an  inch, 
made  into  a  ring  1-lOth  of  an  inch  in  diameter,  be  brought  over  the 
flame.  Though  at  such  a  distance,  it  will  instantly  extinguish  the 
flame,  if  it  be  cold ;  but  if  it  be  held  above  the  flame,  so  as  to  be 
slightly  heated,  the  flame  may  be  passed  through  without  its  being 
extinguished.  That  the  effect  depends  entirely  on  the  power  of  the 
metal  to  abstract  the  heat  of  the  flame,  is  shown  by  bringing  a  glass 
capillary  ring  of  the  same  diameter  and  size  over  the  flame.  This 
being  a  much  worse  conductor  of  heat,  will  not,  even  when  cold, 


LIGHT.  65 

extinguish  it.  If  its  size,  however,  be  made  greater,  and  its  circum- 
ference smaller,  it  will  act  like  the  metallic  wire,  and  requires  to  be 
heated  to  prevent  it  from  extinguishing  the  flame. — Davy  on  Flame. — 
Ure's  Chzm.  Dictionary. 

It  is  upon  this  principle  that   Sir  H.  Davy  constructed  his    Safety 
Lamp,  one  of  the  most  valuable  discoveries  of  the  age.     In  this  in- 
strument there  is  a  succession  of  metallic  orifices  forming  the  wire 
fauze,  which  constitutes  the  cage  of  the  lamp,  and  thus  by  cooling 
own  the  flame  prevents  it  from  communicating  with  the  explosive 
mixture. 

The  same  principle  has  also  been  applied  by  the  Chevalier  Aldini, 
to  the  construction  of  a  robe  for  the  preservation  of  firemen  against 
fire  and  flame.  [Set  SiUiman's  Jour,  xviii.  177,  xx.  96.]  M.  Libri  of 
Florence  ascribes  the  protection  which  Davy's  lamp  affords,  to  the  re- 
pulsion exerted  by  the  metallic  wire  upon  the  flame. — Brewsters  Edin. 
Jour.  ix.  311. 

REFERENCES.  Graham  on  the  Heat  of  Friction— Ann.  of  Phil,  xxviii. 
2(!0.  The  article  Combustion,  in  fJres1  Chem.  Dictionary,  containing  an 
account  of  the  various  theories  on  this  subject — Also,  Thomson*^  Chemistry. 
Davy  on  I 'lame.  RwmfortPs  Experiments  on  the  combustions  of  Woods — See 
his  Essays,  and  Thoinsoifs  Chemistry.  Berzlius  on  the  Blow-pipe.  Lin- 
ton  on  the  colour  of  Flames — Emporium  of  Arts,  v.  457.  PorretCs  observa- 
tions on  the  flame  of  a  Candle — Ann.  of  Phil.  ix.  337.  Sym.  on  Flame — 
Arm.  of  Phil.  viii.  321.  Murray  on  the  same  subject— Ann.  of  Phil.  xvi.  424. 
On  the  construction  of  Furnaces,  and  the  management  of  Fuel — See  Parkes* 
Essays  ;  and  also,  Grains  Operative  Chemist. 

GENERAL  REFERENCES  ON  HEAT.  Count  Rnmford's  Essays. —  Dalian's 
New  System  of  Chemical  Philosophy. — Dr.  Bla(Kts  Lectures,  by  Robinson. 
— Berthollefs  Chemical  Statistics. —  S  cheek's  Treatise  on  Air  and  Fire. — 
Lf she's  Experimental  Inquiry  into  the  Nature  of  Pleat. — Pictefs  Essay  on 
Fire  — Biot's  Precis.  Elementaire. — Murray1  s  System  of  Chemistry  — Thom- 
son's Outline  of  the  Science  of  Heat  and  Electricity. — Library  of  Useful 
Knowledge,  article  Heat. — Lavoisier's  Elements  of  Chemistry. — Aiki/fs  Dic- 
tionary of  Chemistry  and  Mineralogy,  article  Caloric. — AmotCs  Physics,  \\. 
— Lardnef  on  Heat. 


CHAPTER  III. 


LIGHT. 

When  the  sun  rises  above  the  horizon  a  mode  of  communication 
is  established,  which  in  spite  of  his  great  distance,  acquaints  us  with 
his  existence.  This  mode  of  communication  is  called  Light.  And 
bodies  which  can  thus  manifest  their  existence  are  said  to  be  lumin- 
ous, (of  themselves, )  as  the  sun,  the  stars,  &c.  Most  bodies,  however, 
as  we  shall  hereafter  see,  become  luminous  when  their  temperature 
is  sufficiently  elevated,  and  they  lose  this  property  when  they  be- 
come cool.  But  even  when  they  become  opaque,  if  enlightened  by 


66  LIGHT. 

a  luminous  body,  they  acquire  the  property  of  transmitting  light  in 
the  same  way  as  if  they  were  luminous  ;  and  these  bodies  are  said  to 
be  visible  by  reflection. 

Concerning  the  nature  of  light,  philosophers  are  divided  into  two 
classes.  The  one  class  consider  it  to  consist  of  particles  of  matter 
actually  emanating  from  the  luminous  body  ;  the  other  conceive  it 
to  be  transmitted  by  means  of  pulsations  or  vibrations  excited  in  an 
elastic  fluid,  in  the  same  way  that  sound  is  conveyed  through  the  air. 
The  former  opinion  was  adopted  and  maintained  by  Newton,  and  is 
now  generally  received,  as  best  accounting  for  the  phenomena  which 
it  exhibits.*1 

The  consideration  of  the  laws  of  light,  so  far  as  they  relate  to  the 
phenomena  of  its  movement,  and  its  effects  in  producing  vision,  con- 
stitutes the  science  of  Optics  ;  and  are  the  objects,  therefore,  not  of 
Chemistry,  but  of  Natural  Philosophy.  We  shall,  however,  briefly 
notice  the  physical  properties  of  light,  as  they  bear  upon  important 
questions  of  chemical  enquiry. 

The  light  of  the  sun  moves  with  the  velocity  of  192,000  miles  in  a 
second  of  time,  so  that  it  passes  through  the  whole  distance  from  the 
sun  to  the  earth  in  about  eight  minutes. 

Light  is  transmitted  through  the  air  in  straight  lines,  which  are 
called  rays  of  light,  and  it  is  by  means  of  these  that  vision  is  effec- 
ted. 

When  a  ray  of  light  falls  upon  a  polished  surface,  it  is  thrown  off 
or  reflected.  And  the  angles  of  incidence  and  reflection  are  in  this 
case  always  equal,  whatever  may  be  the  obliquity  of  the  incident 
ray. 

A  ray  of  light  passing  obliquely  from  one  medium  to  another,  does 
not  proceed  in  the  same  direction  as  before,  but  is  refracted,  or  bent 
out  of  its  course.  If  the  new  medium  be  denser  than  the  old,  the 
ray  of  light  is  bent  or  reflected  nearer  to  the  perpendicular  ;  but  in 
passing  out  of  a  denser  into  a  rarer  medium,  it  is  refracted  from  the 
perpendicular,  and  there  is  a  constant  proportion  between  the  sine 
of  the  angle  of  incidence  and  that  of  refraction.  Transparent  media, 
also,  not  only  cause  a  change  in  the  direction  of  a  ray,  but  de- 
compose it  into  its  constituent  parts,  an  effect  which  has  been  call- 
ed dispersion. 

When  a  ray  of  light,  in  passing  through  certain  bodies,  (Iceland 
spar  for  example,)  exhibits  a  double  image  of  any  object  viewed 
through  them,  it  is  called  double  refraction.  In  this  case  the  light  is 
divided  into  two  pencils,  the  one  following  the  law  of  ordinary  re- 
fraction ;  the  other  being  differently  affected,  constituting  extraordi- 
nary refraction. 

Light  is  not  a  simple  body,  but  is  capable  of  being  divided  by  the 
prism  into  seven  primary  rays  or  colours,  viz.  red,  orange,  yellow, 

freen,    blue,   indigo,  and  violet.     These  rays  differ  in  their  refrangi- 
ility,  the  red  being  the  least,  and  the  violet  the  most  refrangible. 
The  image  formed  by  the  different  rays,  thus  separated,  is  called  the 

*  Dr.  Brewster  thus  briefly  contrasts  the  two  systems.  **  In  the  Newtonian 
theory,  light  is  supposed  to  consist  of  material  particles  emitted  by  luminous 
bodies;  and  moving  through  space  nith  a  velocity  of  192,003  miles  in  a  se- 
cond. In  the  unduiatory  theory,  an  exceedingly  thin  and  elastic  medium,  call- 
ed ether,  is  supposed  to  fill  all  space  and  to  occupy  the  intervals  between  the 
particles  of  all  material  bodies." — Optics,  134. 


LIGHT.  67 

solar  spectrum.  According  to  Dr.  Wollaston,  the  spectrum  consists 
of  four  colours  only,  viz.  red,  green,  blue  and  violet,  and  these  oc- 
cupy spaces  in  the  proportion  of  16.23.  36.25.  These  different  colour- 
ed rays  being  collected  by  a  lens  into  a  focus,  again  produce  colour- 
less light.  Again,  Dr.  Brewster  gives  a  new  analysis  of  solar  light 
indicating  three  primary  colours,  forming  coincident  spectra  of  equal 
length.— Edin.  Jour,  of  Science,  N.  S.  v.  197. 

Sir  W.  Herschel  found  that  the  prismatic  colours  differ  in  their  illu- 
minating power.  The  orange  possesses  this  property  in  a  higher  de- 
gree than  the  red ;  and  the  yellow  rays  illuminate  bodies  still  more 
perfectly.  The  maximum  of  illumination  lies  in  the  brightest  yellow 
or  palest  green.  The  green  itself  is  nearly  equally  bright  with  the 
yellow;  but  from  the  full  deep  green,  the  illuminating  power  de- 
creases very  sensibly.  That  of  the  blue  is  nearly  equal  to  that  cf 
the  red  ;  the  indigo  has  much  less  than  the  blue  ;  and  the  violet  is  very 
deficient. —Phil.  Trans.  1800. 

The  heating  powers  of  the  rays  follow  a  different  order.  If  the 
bulb  of  a  very  sensible  thermometer  be  moved  in  succession  through 
the  differently  coloured  rays,  it  will  be  found  to  indicate  the  greatest 
heat  in  the  red  rays  ;  next  in  the  green,  and  so  on,  in  a  diminishing 
progression  to  the  violet.  But  when  it  is  removed  entirely  out  of  the 
confines  of  the  red  rajs,  but  with  its  ball  still  in  the  line  of  the  spec- 
trum, it  rises  even  higher  than  in  the  red  rays,  and  continues  to  rise, 
till  removed  half  an  inch  beyond  the  extremity  of  the  red  rays.  It 
was  hence  inferred  by  Herschel,  that  there  exists  in  the  solar  beam 
a  distinct  kind  of  ray,  which  causes  heat,  but  not  light  ;  and  that 
these  rays  being  less  refrangible  than  the  luminous  ones,  deviate 
in  a  less  degree  from  their  original  direction  in  passing  through 
the  prism. 

Though  the  truth  of  the  statement,  that  the  prismatic  colours  pos- 
sess different  heating  powers,  has  been  confirmed  by  all  succeeding 
experiments,  there  has  been  much  difference  with  regard  to  the  spot 
at  which  the  heat  is  a  maximum.  The  opinion  of  Herschel  has  how- 
ever been  fully  confirmed  by  the  recent  observations  of  Mr.  Seebeck. 
—Edin.  Jour,  of  Science,  i.  358. 

When  the  solar  rays  traverse  a  biconvex  lens,  they  are  collected  to- 
gether in  a  focus,  but  the  focus  of  the  calorific  rays  is  a  short  dis- 
tance behind  that  of  the  luminous,  showing  that  they  are  differently 
refracted. — Berzelius. 

Beyond  the  confines  of  the  spectrum  on  the  other  side,  viz.  a  little 
beyond  the  violet  ray,  the  thermometer  is  not  affected  :  but  in  this 
place  it  is  remarkable  that  there  are  also  invisible  rays  of  a  different 
kind  which  produce  all  the  chemical  effects  of  the  rays  of  light,  and 
with  even  greater  energy.  It  is  well  known  that  if  chloride  of  silver 
is  exposed  to  the  direct  light  of  the  sun,  it  is  speedily  changed  from 
white  to  black.  The  rays  separated  by  the  prism  possess  this  power 
of  blackening  chloride  of  silver  in  various  degrees.  The  blue  rays 
for  example,  effect  a  change  in  15  seconds,  which  the  red  require  2& 
minutes  to  accomplish  ;  and,  generally  speaking,  the  power  diminish- 
es as  we  recede  from  the  violet  extremity.  But  entirely  out  of  the 
spectrum  the  effect  is  still  produced.  Hence  it  is  inferred  that  there 
are  certain  rays  which  excite  neither  heat  nor  light  ;  and  which,  from 
their  peculiar  agency,  have  been  called  Chemical  or  de-oxidizing 
rays. 

It  appears,  therefore,  that  a  ray  of  light  contains  three  distinct  sets 
of  rays,  viz.  The  illuminating,  the  heating,  and  the  chemical  or  deoxi- 


63  LIGHT. 

dizing.  It  may  also  be  added,  that  the  more  refrangible  rajs  of  light 
seem  to  possess  the  property  of  rendering  steel  or  iron  magnetic  :  a 
property  discovered  by  Dr.  Morichini  of  Rome,  and  confirmed  by  the* 
experiments  of  Mrs.  Somerville,  who  succeeded  in  magnetizing  a  sew- 
ing needle  by  less  than  two  hours  exposure  to  the  violet  ray.  Phil. 
Trans.  1828.  This  effect,  however,  has  been  much  questioned,  and  is 
wholly  rejected  by  Priess  and  Moser. — Brewster's  Edin.  Jour.  N.  S.  ii. 
225. 

There  are  many  bodies  in  nature  which  possess  the  property  of  giv- 
ing out  light  without  any  sensible  emission  of  heat ;  and  these  arc 
commonly  known  by  the  name  of  phosphori.  The  leading  divisions  of 
these  substances  are  : 

1.  Solar  phosphori;  or  those  which  require  a  previous  exposure  to 
solar  or  other  light  to  become  luminous.     Such  are  Canton's,  Bald- 
win's and  the  Bolognian  phosphori,  which  will  be  described  hereafter. 
To  the  same  class  belong  several  natural  bodies  which  retain  light  arid 
give  it  out  unchanged.     Thus,  snow  is  a  natural  solar  phosphorus. 

2.  Phosphori  from  heat;  or  those  which  become  luminous,   by  heat 
alone.     Thus  powdered  fluate  of  lime  becomes  luminous,  when  throwu 
on  an  iron  plate  raised  to  a  temperature  rather  above  that  of  boiling 
water,  and  one  of  its  varieties  known  to  mineralogists  by  the  name  of 
Chlorophane,  gives  out  abundantly  an  emerald  green  light,  by  the  mere 
heat  of  the  hand.     The  yolk  of  an  egg,  when  dried,  becomes  luminous 
on  being  heated  ;  and  so  also  do  spermaceti,  wax  and  tallow,  during 
liquefaction.     To  exhibit  the  last  mentioned  fact,  it  is  only  necessary 
to  place  a  lump  of  tallow  on  a  coal,  heated  below  ignition,  making  the 
experiment  in  a  dark  room. — Brcwster.  on  the  phosphorescence  of  certain 
fluids,  Edin.  Jour,  of  Science,  iv.  178. 

3.  Spontaneous  phosphori ;  or  those  animal  and  vegetable  substances 
which  emit  light  spontaneously  at  common  temperatures,  without  the 
necessity  of  previous  exposure  to  light.     This  property  is  possessed  in 
a  remarkable  degree  by  fish  and  some  other  marine  animals  ;  and  in 
these  it  makes  its  appearance  before  the  commencement  of  putrefac- 
tion, and  ceases  when  the  latter  is  completely  established.     The  lumi- 
nosity of  sea  water  is  ascribed  to  the  presence  ofanimalcnlac,  which  arc« 
naturally  phosphorescent.     Of  vegetable  matters  which  become  lumi- 
nous, the  most  remarkable  is  decayed  wood. 

The  chemical  effects  of  light  are  very  evident  in  the  case  of  a  mix- 
ture of  chlorine  and  hydrogen,  which  explodes  and  produces  muriatic 
acid.  Again,  chlorine  and  carbonic  oxide  have  scarcely  any  tendency 
to  unite,  even  at  high  temperatures,  when  light  is  excluded  ;  but  ex- 

Eosed  to  the  solar  rays,  they  enter  into  chemical  union.     Chlorine  also 
as  but  little  action  on  water  unless  exposed  to  light.     To  the  same 
class  of  the  chemical  effects  of  light,  may  be  referred  the  decomposition 
of  nitric  acid,  and  the  decomposition  or  change  of  colour  of  the  salts 
of  gold  and  silver. 

The  green  colour  of  vegetables  is  also  owing  to  the  influence  of  solar 
light.  [For  additional  facts  on  the  subject  of  the  chemical  influence  oi 
Light,  see  Phil.  Mag.  and  Ann.  vii.  46^.] 

For  measuring  the  intensities  of  light  from  various  sources,  an  in- 
strument has  been  constructed  which  is  called  the  Photometer.  That 
of  Mr.  Leslie  is  founded  on  the  principle,  that  light  in  proportion  to 
its  absorption,  produces  heat.  The  degree  of  heat  produced,  and  con- 
sequently of  light  absorbed,  is  measured  by  the  expansion  of  a  confined 
portion  of  air.  It  is  merely  a  very  chlicate  and  small  differential  ther- 


69 

mometer,  enclosed  in  a  thin  and  pellucid  glass  tube.  One  of  the  balls, 
however,  is  rendered  opake,  either  by  tinging  the  glass  or  covering  it 
with  a  pigment ;  and  hence  this  ball,  when  the  instrument  is  suddenly 
exposed  to  light,  becoming  warmer  than  the  clear  bulb,  indicates  the 
effect  by  the  depression  of  the  fluid. — Leslie  s  Enquiry. 

Some  objections  to  this  instrument  have  been  stated,  for  which  we 
must  refer  the  reader  to— the  Rev.  Mr.  Powell's  Historical  Sketch  of 
Photometry,  in  the  Ann.  of  Phil,  xxvii.  371,  where  will  also  be  found 
a  notice  of  Rumford's  Photometer,  and  of  that  proposed  by  Dr.  Brew- 
ster  ; — and  to  Mr.  Ritchie's  paper  on  Leslie's  Photometer,  in  ihe  Edin. 
Jour,  of  Science,  ii.  321.  339.  and  iii.  104.  Brande's  modification  ot 
Leslie's  Photometer,  is  described  in  his  Journal,  viii.  220.* 

The  sources  of  light  are,  the,  Sun  and  Stars,  Chemical  action,  Heat 
and  Percussion.  The  first  of  these  we  have  already  noticed. 

Chemical  action.  Whenever  combustion  forms  a  part  of  the  phe- 
nomena, light,  as  is  well  known,  is  given  out  ;  but  light  is  also  evolved 
in  other  instances,  where  nothing  like  combustion  takes  place.  Thus, 
freshly  prepared  magnesia,  added  suddenly  to  highly  concentrated  sul- 
phuric acid,  exhibits  a  red  light.  When  the  vapour  arising  from  a  so- 
lid, benzoic  acid  for  instance,  is  condensed,  light  is  evolved,  and  fused 
boracicacid,  when  passing  to  a  solid  form,  exhibits  the  same  phenome- 
non. So  also  some  substances,  during  the  process  of  crystallization 
give  out  scintillations  of  light,  as  sulphate  of  potassa  and  fluoride  of 
sodium.  —  Berzelius,  i.  52. 

But,  perhaps  the  most  intense  artificial  light  is  that  which  is  obtain- 
ed by  directing  the  flame  of  the  oxy  hydrogen  blow-pipe  upon  a  small 
spherule  of  lime,  about  a  quarter  of  an  inch  in  diameter.  The  lime 
from  chalk  is  best  adapted  to  this  purpose,  as  it  is  most  easy  to  give  it 
the  proper  form.  The  light  thus  produced  is  so  brilliant  as  scarcely  to 
be  borne  by  the  naked  eye,  and  its  use  is  therefore  suggested  for  illu- 
minating light  houses.  It  acts  also  as  solar  light  does  on  mixtures  of 
chlorine  and  hvdrogen,  and  on  chloride  of  silver. — Drummond,  Phil. 
Trans.  1826.  "Also  Edin.  New  Phil.  Jour.  i.  182. 

Percussion.  Light  is  also  evolved  by  percussion  and  friction.  Thus, 
two  pieces  of  common  bon»et  cane,  rubbed  strongly  against  each  other 
ia  the  dark,  emit  a  faint  light.  Two  pieces  of  borax,  quartz  or  sugar, 
have  the  same  property  in  a  more  eminent  degree.  Some  of  the  gases 
also,  when  highly  compressed,  give  out  light. 

Heat.  When  heat  is  applied  to  bodies,  and  continually  increas9d, 
there  is  a  certain  temperature  at  which  they  become  luminous  ;  and 
the  body  is  then  said  to  be  red  hot,  or  incandescent. 

The  temperature  at  which  solids  in  general  begin  to  shine  in  the 
dark,  is  between  600  and  7003  F.  ;  but  they  do  not  appear  luminous  in 
broad  daylight,  till  they  are  heated  to  about  1000°  F.  The  colour  of 
incandescent  bodies  varies  with  the  intensity  of  the  heat.  The  first 
degree  of  luminousness  is  an  obscure  red.  As  the  heat  augments,  the 
redness  becomes  more  and  more  vivid,  till  at  last  it  acquires  a  full  red 
glow.  Should  the  temperature  still  continue  to  increase,  the  charac- 

*  The  indications  of  these  photometers  cannot  be  depended  on  when  there 
is  much  difference  in  the  colour  of  the  lights.  In  such  cases  the  best  method 
of  obtaining  approximative  results,  is  by  observing  the  d'sfarice  from  each 
light  at  which  any  given  object,  as  a  printed  page,  ceases  to  be  distinctly  visi- 
ble. The  Illuminating  power  of  the  lights  so  cosnpared  is  as  the  squares  of 
their  distances. 


ELECTRICITY. 

ter  of  the  glow  changes,  and  by  degrees  becomes  white,  shining  with 
increasing  brilliancy  as  the  intensity  of  the  heat  augments.  Liquids 
and  gases  likewise  become  incandescent  when  strongly  heated ;  but  a 
very  high  temperature  is  required  to  render  a  gas  luminous,  more  than 
is  sufficient  for  heating  a  solid  body  even  to  whiteness.  The  different 
kinds  of  flame,  as  of  the  fire,  candles  and  gas  light,  are  instances  of  in- 
candescent gaseous  matter. 

REFFERENCES.  Biotas  Traite  Precis,  ii.  Brewster's  Optics. —Library 
of  Useful  knowledge,  Art.  Double  Refraction  and  Polarization  of  Light. 
Thomson"1  s  Chemistry,  i.  Aikiifs  C/iem.  Diet.  Art.  Phosphori.  Lieut.  In- 
galls  on  the  Luniinousness  of  the  Ocean — Trans.  Alb.  Institute,  \.  Osann 
on  some  New  Bodies,  which  absorb  Light  strongly — Edin.  New  Phil.  Jour. 
\\.  153.  Mr.  Powell  on  Solar  Light  and  Heat,  Ann.  of  Phil,  xxiii.  and 
xxiv.  Also,  remarks  by  the  same  author  on  Light  and  Heat  from  Terrestrial 
Sources,  Ann.  of  Phil.  xxir.  181,  xxv.  201,  359,  401,  and  the  same  author's 
recent  Report  on  Radiant  Heat.  RiimforcCs  Inquiry  concerning  the  Chemic- 
al Properties  that  have  been  attributed  to  Light,  Phil.  Trans,  and  Repert. 
of  Arts,  \st  series,  x.  189.  In  this  paper  the  aut/ior  attempts  to  show  that  the 
chemical  properties  usually  ascribed  to  light,  are  the  mere  effects  of  the  heat 
•which  is  generated,  or  excited,  by  the  ligkt  that  is  absorbed  by  the  bodies  in 
which  these  changes  are  supposed  to  ta/ce  place.  On  the  identity  of  Light  and 
Heat,  see  also  ChaptaVs  Client,  i. 


CHAPTER  IV. 

ELECTRICITY. 

The  term  Electricity,  applied  to  the  unknown  cause  of  a  peculiar 
kind  of  attraction,  is  derived  from  the  Greek  word  electron,  amber,  be- 
cause the  electric  property  was  first  noticed  in  this  substance. 

In  my  remarks  upon  this  subject,  I  shall  briefly  notice,  1st.  The 
general  or  elementary  facts  of  the  science  :  2d.  The  theory  proposed 
to  account  for  these  facts  :  and  3d.  The  effects  of  accumulated  elec- 
tricity. 

I.  The  general  facts  of  electricity  may  be  conveniently  reduced  to  the 
following,  viz  :  EXCITATION — ATTRACTION — REPULSION — DISTRIBUTION — 
TRANSFERANCE — and  INDUCTION. — Library  of  Useful  Knowledge,  Art. 
Electricity. 

All  these  facts  can  be  shown  with  the  simple  apparatus  of  a  clean 
and  dry  glass  tube,  a  dry  silk  handkerchief,  and  a  few  pith  balls,  sus- 
pended by  silken  threads.  But  they  are  much  more  strikingly  exhibit- 
ed if  we  employ  an  Electrical  Machine,  an  instrument  which  consists 
essentially  of  a  circular  plate  of  glass,  or  a  glass  cylinder,  fixed  upon 
an  axle,  and  pressed  by  a  cushion  or  Rubber,  which  is  generally  be- 
smeared with  a  soft  compound,  or  an  amalgam  of  mercury  and  tin 
with  grease.  At  a  short  distance,  is  placed  a  metallic  cylinder,  sup- 
ported by  glass  feet,  called  the  Prime  Conductor,  which  at  the  end 
next  the  glass,  has  commonly  a  few  projecting  teeth  made  of  pointed 
wire. 


ELECTRICITY.  71 

If  now  the  rubber  is  connected  by  a  small  chain  or  otherwise,  with 
the  table  or  floor,  and  the  glass  cylinder  or  plate  made  to  revolve  upon 
its  axle,  a  crackling  noise  is  heard,  accompanied  with  a  luminous  ap- 
pearance, and  on  bringing  the  knuckle  or  a  rounded  metallic  knob, 
near  the  prime  conductor,  a  spark  issues,  accompanied  with  a  snap  or 
slight  report,  and  with  a  pricking  sensation  when  the  knuckle  is  pre- 
sented. The  glass  is  in  this  case  said  to  be  excited,  and  the  substances 
thus  susceptible  of  excitation  are  termed  Electrics,  in  contradistinction 
to  such  as  are  not  excited  by  a  similar  process,  and  which  are  termed 
Non- electrics.  This  distinction,  however,  is  not  founded  in  nature,  for 
electricity  may  be  excited  in  all  solid  bodies  by  friction,  though  for 
this  purpose  the  friction  is  to  be  applied  in  different  ways. 

Attraction  and  Repulsion.  If,  while  the  prime  conductor  is  charged 
with  electricity,  a  light  body,  as  a  pith  ball,  suspended  by  a  silken 
thread,  be  brought  near  it,  it  is  attracted  by  the  conductor  and  adheres 
to  it  for  a  certain  time  ;  after  which  it  recedes,  or  is  repelled  from  it. 
This  change,  however,  does  not  take  place  in  all  bodies  with  equal  ra- 
pidity ;  some  require  a  considerable  time  before  they  begin  to  recede  ; 
others,  and  especially  metallic  bodies,  are  repelled  the  instant  after 
contact.  The  phenomena  of  attraction  and  repulsion  can  also  be  stri- 
kingly exhibited  by  several  amusing  experiments  ;  as  the  electrical 
bells,  the  electrical  dance,  &c. 

It  appears  therefore  that  when  bodies  are  electrified  by  contact  with 
excited  glass,  they  are  repelled  by  it.  The  same  thing  also  takes  place, 
when  they  are  electrified  by  excited  resins.  But  when  a  body  electri- 
fied by  glass  is  brought  near  a  body  electrified  by  the  resins,  instead  of 
repelling  each  other,  they  are  now  attracted.  From  these  facts  the 
following  general  laws  have  been  deduced,  viz  :  Bodies  similarly  elec- 
trified, repel  each  oilier  ;  bodies  differently  electrified,  attract  each  other. 

It  should  be  remarked  also,  that  the  production  or  excitation  of  one 
kind  of  electricity  is  always  attended  by  the  excitation  of  the  other. 
Thus  when  glass  is  rubbed  by  silk  or  cloth,  they  assume  opposite  elec- 
trical states.  This  can  be  shown  very  strikingly  by  insulating  the 
rubber  of  an  ordinary  machine. 

Distribution  and  Transference.  If  a  pith  ball  or  metallic  globe,  sus- 
pended by  silk,  after  having  been  in  contact  with  a  charged  conductor, 
be  removed,  and  the  ball  be  brought  near  to  another  ball,  suspended  in 
a  similar  manner,  they  will  approach  each  other  and  then  again  recede. 
This  second  ball,  when  brought  near  a  third,  will  exhibit  the  same 
phenomena,  although  in  a  less  striking  manner,  as  the  amount  of  elec- 
tricity becomes  gradually  diminished  by  these  successive  operations. 
It  is  evident,  therefore,  that  the  electricity  communicated  to  the  first 
ball  may  be  communicated  to  the  second,  and  that  from  the  second  to 
the  third,  &c.  in  the  same  mariner  that  heat  is  transferred  from  one 
body  to  another. 

If,  however,  we  bring  in  contact  with  a  ball  thus  electrified,  the 
hand  or  a  metallic  body,  we  observe,  in  some  instances,  a,  spark,  arid 
it  loses  the  property  of  attracting  another  unelectrified  ball,  in  conse- 
quence of  the  electricity  having  passed  into  the  body.  But  if  a  tube 
of  glass  be  substituted  for  the  hand  or  the  metallic  rod,  the  body 
touched  retains  the  whole  of  its  electricity.  We  therefore  infer  that 
some  bodies,  as  glass,  are  incapable  of  conducting  electricity,  while 
others,  such  as  the  metals  and  the  human  bodv,  readily  convey  that 
influence.  Hence  the  division  of  bodies  into  conductors  and  non-con- 
ductors— the  latter  being  those  which  are  electrics,  and  the  former 


ELECTRICITY. 

non-electrics.  The  two  qualities,  of  a  capability  of  excitation  and  a 
power  of  conducting  electricity,  appear  to  be  incompatible  with  each 
other;  for  the  one  is  always  found  to  diminish  in  proportion  as  the 
other  increases.  The  permanence  of  electricity  in  metallic  bodies, 
which  are  suspended  in  the  air  by  silk  threads,  shows  that  the  air,  as 
well  as  silk,  is  a  non-conductor.  Bodies  which,  in  this  way,  are  sur- 
rounded on  all  sides  by  non-conductors,  are  said  to  be  insulated.  The 
air,  however,  when  it  contains  much  moisture,  becomes  a  conductor  ; — 
and  the  conducting  powers  of  most  bodies  are  influenced  by  changes 
of  form  and  temperature.  The  metals  are  the  most  perfect  conduct- 
ors ;  the  resins,  amber  and  gum  lac,  the  most  perfect  non-conductors. 

The  phenomena  of  the  transference  of  electricity  are  modified  by 
the  form  of  bodies.  Hence  the  different  effects  which  are  observed 
when  conductors  in  the  form  of  balls,  or  pointed  ones,  are  charged 
with  the  fluid.  In  the  former  case  the  electricity  is  equally  diffused 
over  the  surface  of  the  ball,  and  it  has  a  low  intensity  ;  in  the  latter, 
the  intensity  is  greatly  increased  at  the  extremities,  and  this  is  accom- 
panied with  a  powerful  tendency  in  the  fluid  to  escape.* 

Induction.  It  has  been  shown  that  when  an  excited  electric  is 
brought  near  to  an  insulated  ball,  the  latter  is  attracted.  This  arises 
from  the  fact  that  the  natural  state  of  the  body  has  been  disturbed,  and 
an  electricity  of  an  opposite  kind  has,  as  it  is  said,  been  induced,  in 
that  part  of  the  ball  nearest  to  the  electric ;  whereas  that  part  of  the 
ball  which  is  most  distant  has  the  same  electrical  state  as  the  electric. 
Attraction,  therefore,  is  in  all  cases,  the  result  of  this  principle  of  in- 
duction. But  when  the  ball  comes  in  contact  with  the  electric,  it  soon 
becomes  of  the  same  electric  condition,  and  repulsion  is  observed. 

This  principle  can  be  more  satisfactorily  shown  by  the  Leyden  Jar. 
the  inner  side  of  which,  by  communication  with  the  charged  conduc- 
tor of  a  machine,  is  rendered  positive,  whereas  the  outer  side  is  ren- 
dered negative  by  induction.  When  these  two  sides  are  brought  into 
contact,  by  means  of  a  Discharger,  the  restoration  of  the  equilibrium 


*  As  the  terms  quantity  and  intensity  or  tension  are  often  employed  in 
treating1  of  electricity  and  galvanism,  it  may  be  proper  to  explain  them  more 
particularly.  The  former  implies  the  actual  quantity  of  electric  power  in  any 
body;  whereas  intensity  or  tension,  signifies?  the  stale  of  electricity  indicated 
by  the  electrometer,  and  ils  power  of  flying  off  from  surfaces  and  passing 
through  a  certain  stratum  of  air  or  other  ill  conducting  medium.  Tension, 
appears  to  depend  upon  the  quantity  of  electricity  accumulated  on  a  given 
space;  arid  hence  the  intensity  of  those  substances  is  the  greatest,  which  have 
the  greatest  excess  or  deficiency  of  electricity  in  proportion  to  their  surface. 
Suppose  a  charged  Leyden  jar  to  give  a  spark  when  discharged,  of  one  inch 
in  length,  another  uncharged  jar,  communicating  with  the  former,  would  upon 
the  same  quantity  of  electricity  being  thrown  in,  reduce  the  length  of  the, 
spark  to  half  an  inch  :  thus  the  quantity  of  electricity  remaining  the  same,  its 
intensity  is  diminished  by  one-half,  by  its  distribution  over  a  larger  surface. 

This  accounts  for  the  freedom  with  which  electricity  is  given  off  by  pointed 
conductors.  For  though  the  quantity  of  electricity  accumulated  on  a  sharp 
point,  may  be  very  small,  it  is  still  large  when  compared  with  the  surface.  The 
electric  tension  of  the  point  is' the  re  fore  very  great,  and  hencex  if  positive,  it 
gives  off  electricity  to  surrounding  bodies,  and  if  negative,  receives  it  from 
them,  with  extreme  velocity. 


ELECTRICITY.  73 

of  electricity  is  attended  with  a  snap  or  report.  These  explanations, 
however,  will  be  better  understood,  from  the  following  brief  exposition 
of  the  theory  of  electricity. 

II.  Theory.  The  phenomena  of  electricity  are  ascribed  by  some 
philosophers  to  the  agency  of  one  fluid,  and  by  others  to  that  of  two 
distinct  fluids.  The  latter  opinion  was  originally  proposed  by  Dufay, 
and  is  almost  exclusively  adopted  in  France  ;  the  former  was  proposed 
by  Franklin,  and  is  generally  received  in  England  and  America.  It  is 
somewhat  singular  that  most  of  the  phenomena  can  be  equally  well 
explained  upon  either  hypothesis,  and  as  has  been  remarked,  "the 
selection  depends  more  upon  the  taste  than  the  judgment  of  the  in- 
quirer." The  former  of  these  theories  is  adopted  in  the  present  work. 

Electricity,  according  to  the  Franklinian  hypothesis,  is  a  subtle, 
highly  elastic  and  imponderable  fluid,  which  pervades  all  material 
bodies,  and  is  capable  of  moving  through  the  pores  or  substances 
of  various  kinds  of  matter.  It  moves  through  bodies  with  various 
degrees  of  facility,  through  some,  as  the  conductors  or  non-electrics, 
passing  freely  ;  through  others,  as  the  electrics  or  non-conductors, 
with  great  difficulty.  The  particles  of  this  fluid  repel  one  another, 
and  attract  the  particles  of  all  other  matter,  with  a  force  varying  in- 
versely as  the  square  of  the  distance. 

Bodies,  on  this  hypothesis,  are  supposed  to  be  in  their  natural  state, 
with  regard  to  electricity,  when,  the  repulsion  of  the  particles  of  the 
fluid  is  exactly  balanced  by  the  attraction  of  the  matter  for  the  same 
particles.  In  this  state  bodies  are  supposed  to  be  saturated  with  the 
electric  fluid.  When  they  contain  a  quantity  greater  than  this,  they 
are  said  to  be  positively  electrified,  or  over  charged  with  the  electric  fluid  ; 
when  the  quantity  is  less  than  this,  the  body  is  said  to  be  negatively 
electrified,  or  under  charged.  These  different  states  are  sometimes  re- 
presented by  the  terms  plus  and  minus. 

According  to  this  theory,  when  a  body  is  positively  electrified,  or 
has  more  than  its  natural  quantity  of  electricity,  the  surplus,  in  con- 
sequence of  the  mutual  repulsion  of  its  particles,  has  a  tendency  to 
escape,  and  this  continues  until  the  body  is  reduced  to  its  natural 
stats.  Again,  when  a  body  is  negatively  electrified,  or  contains  less 
than  its  natural  quantity  of  electricity,  it  has  a  tendency  to  attract  the 
fluid  from  all  sides,  until  the  neutral  state  is  again  restored.  When  a 
glass  globe  or  tube  is  excited  by  silk,  the  electricity  leaves  the  silk  and 
is  accumulated  on  the  glass  ;  the  silk,  therefore,  becomes  negative  and 
the  glass  positive. 

There  was  however,  one  defect  in  the  original  Franklinian  theory, 
which  was  detected  by  Aepinus  and  confirmed  by  Cavendish,  and 
which  rendered  it  necessary  to  add  another  condition  to  it.  The  de- 
fect was,  that  while  the  repulsion  which  is  observed  between  two  po- 
sitively electrified  bodies  was  easily  accounted  for,  the  repulsion  be- 
tween bodies  negatively  electrified  was  left  without  explanation.  By 
the  theory,  this  could  not  be  referred  to  the  repulsion  of  the  particles 
of  electric  fluid,  for  they  were  supposed  to  contain  less  than  their  na- 
tural amount.  It  was  necessary,  therefore,  to  annex  the  additional 
condition,  that  particles  of  matter  uncomlined  with  electricity,  exert  a  re- 
pulsive action  upon  one  another.  Without  this,  a:s  can  easily  be  shown, 
we  are  not  only  unable  to  account  for  the  repulsion  existing  between 
bodies  negatively  electrified,  but  also  for  the  want  of  action  between 
two  neutral  bodies.  The  repulsion  of  two  negatively  electrified  bodies, 
therefore,  can  only  be  considered  as  the  result  of  the  repulsion  of  the 
particles  of  matter. 


74  ELECTRICITY. 

It  will  now  be  seen  that  the  theory,  as  thus  developed,  satisfactorily 
explains  the  elementary  facts  which  have  been  set  forth,  and  will  bear 
application  to  all  the  phenomena  which  electricity  presents.  Thus, 
by  the  operation  of  friction,  the  natural  state  of  bodies  is  dis- 
turbed ;  and,  as  the  result  of  this,  there  is  an  accumulation  of  electri- 
city on  one  side  and  a  diminution  on  the  other,  and  the  bodies  are 
excited.  The  phenomena  of  attraction  and  ^repulsion,  of  distribution 
and  transference,  can  also  be  readily  accounted  for.  And  the  law  of 
induction,  moreover,  is  a  consequence  of  the  theory.  For  when  a 
body  overcharged  with  electricity  is  presented  to  a  neutral  body,  the 
repulsive  force  existing  among  the  particles  of  electricity  in  the  former 
has  a  tendency  to  drive  the  electricity  from  the  nearest  part  of  the  neu- 
tral body,  if  a  conductor,  to  that  which  is  the  most  remote.  The  near- 
est end  of  the  body,  therefore,  becomes  negatively  electrified,  while 
the  remote  end  becomes  positively  electrified.  Now  if,  instead  of  a 
positively  electrified  body,  we  bring  a  negatively  electrified  one  near 
a  neutral  body,  its  attraction  for  the  fluid  in  the  second  body  will  cause 
an  accumulation  in  the  nearest  end,  and  of  course  a  deficiency  in  the 
remote  end. 

For  the  purpose  of  ascertaining  when  a  body  is  electrified,  and  also 
the  intensity  or  degree  to  which  it  is  excited,  instruments  have  been 
constructed  which  are  called  Electroscopes  and  Electrometers.  Al- 
though the  term  electrometer  is  often  indiscriminately  applied  to  both 
those  instruments,  the  latter  denotes  the  intensity  of  electricity,  the 
former  merely  indicates  excitement  and  the  electrical  state  by  which 
it  is  produced. 

One  of  the  simplest  electroscopes  is  that  of  Hauy,  which  consists  of 
a  light  metallic  needle,  terminated  at  each  end  by  a  light  pith  ball, 
which  is  covered  with  gold  leaf,  and  supported  horizontally  by  a  cap 
at  its  centre,  on  a  fine  point.  The  attractive  or  repulsive  power  of 
any  electrified  body,  presented  to  one  of  the  balls,  will  be  indicated  by 
the  movements  of  the  needle.  In  some  cases,  however,  it  is  more 
convenient  to  employ  a  pair  of  similar  balls,  suspended  from  a  brass 
ball,  fixed  to  the  end  of  a  glass  handle,  by  very  fine  silver  wires,  or 
by  hempen  threads,  previously  steeped  in  a  solution  of  salt  and  after- 
wards dried.— L.  U.  K. 

Electrometers  are  constructed  upon  the  principle,  that  the  more 
highly  an  insulated  conductor  is  charged  with  electricity,  the  more 
powerful  is  the  repulsion  which  it  communicates  to  bodies  which  are 
brought  near  it.  Henley's  Quadrant  Electrometer,  is  in  common  use. 
Bennett's  Gold  Leaf  Electrometer,  is  not  only  a  more  delicate  instru- 
ment, but  we  are  enabled  by  it  to  discriminate  between  positive  and 
negative  electricity.  It  consists  essentially  of  a  cylindrical  glass  bot- 
tle, with  its  apertures  closed  by  a  brass  plate,  from  the  centre  of 
which  two  slips  of  gold  leaf  are  suspended.  The  brass  plate,  with  its 
slips  of  gold  leaf,  are  thus  insulated,  and  the  latter  prevented  from  be- 
ing moved  by  currents  of  air,  by  the  glass  with  which  they  are  sur- 
rounded. The  approach  of  any  electrified  body,  even  though  feebly 
excited,  to  the  brass  plate,  is  immediately  detected  by  the  divergence 
of  the  leaves.  If  the  divergence  be  increased  by  the  approach  of 
flint  glass  excited  by  silk,  the  electricity  is  said  to  be  positive  ;  if  the 
divergence  be  diminished,  they  are  said  to  be  negatively  electrified. — 
This  instrument  is,  strictly  speaking,  an  electroscope. 

The  most  perfect  electrometer  for  measuring  small  quantities  of 
electricity,  is  the  apparatus  described  by  Coulomb,  and  to  which  he 
has  given  the  name  of  the  Torsion  Balance,  for  a  description  of  which 


ELECTRICITY.  75 

we  must  refer  to  elementary  works  on  Natural  Philosophy,  or  to  the 
Library  of  Useful  Knowledge,  art.  Electricity. 

III.  Effects  of  Electricity  upon  bodies.  Independently  of  electrical 
attraction  and  repulsion,  it  does  not  appear  that  the  simple  accumula- 
tion of  electricity  in  any  quantity  in  bodies,  as  long  as  it  remains  qui- 
escent, produces  the  least .  sensible  change  in  their  properties.  A 
person  standing  on  an*  insulating  stool,  may  be  charged  with  any 
quantity  of  electricity  from  a  machine,  without  being  perceptibly  af- 
fected, until  the  equilibrium  of  the  fluid  is  disturbed,  by  drawing 
sparks  from  his  body  or  from  the  prime  conductor  with  which  he  may 
be  in  communication.  It  is  the  passage  of  electricity  therefore,  which 
produces  the  effects  now  to  be  noticed. 

When  this  passage  is  uninterrupted,  as  is  the  case  in  rods  of  metal, 
no  perceptible  change  in  the  mechanical  properties  of  the  body  is 
produced.  But  very  considerable  effects  are  produced,  either  if  the 
body  is  so  small  as  not  to  admit  the  whole  quantity  of  electricity  to 
pass  with  perfect  freedom ;  or  if  the  body,  though  large,  is  deficient 
in  conducting  power. 

The  effect  of  electricity  may  be  conveniently  arranged  under  the 
following  heads,  viz. 

1.  The  mechanical  effects,  which  can  be  illustrated  by  various  experi- 
ments ;    as   by  passing  a  charge    of  electricity  through  a  capillary 
tube  containing  mercury,   oil,  water,  alcohol  or  ether  ;  or  by  passing 
it  through  a  small  plate  of  glass,  a  piece  of  pasteboard,   a  card,  or 
through  the  leaves  of  a  book. 

2.  The  evolution  of  heat.     The  ignition  and  fusion  of  the  metals  by 
the  electric  dischage,  are  phenomena  which  have   been  long  observ- 
ed.    Thus  a  very  fine  wire  may  be  fused  by  a  powerful  Leyden  bat- 
tery, or  if  the  wire  be   sufficiently  fine,   by  a  single  jar  ;  and  so  also 
alcohol,  ether  and  spirits  of  turpentine  may  be   inflamed  by  the  spark 
from  the  prime  conductor,  as  well  as  by  the  discharge  from  the  jar. 
Gun-powder  may  be  fired  by  partly  interrupting  the  electric  circuit,  as 
by  causing  the  wire  or  chain  to  pass  through  a  vessel  of  water. 

Light  as  well  as  heat  are  emitted  during  the  electrical  discharge,  at 
every  point  where  the  circuit  is  either  interrupted  or  is  occupied  by 
bodies  of  inferior  conducting  powers.  Thus  a  moderate  charge  from 
a  Leyden  jar  will  produce  a  bright  spark  when  made  to  pass  through 
water,  and  the  spark  is  still  more  luminous  in  oil,  alcohol  or  ether, 
which  are  worse  conductors  than  water  ;  on  the  contrary,  in  fluids  of 
greater  conducting  power,  there  is  greater  difficulty  of  eliciting  elec- 
tric light. 

3.  The  chemical  effects.     These  will  be  more  strikingly   shown  when 
treating  of  Galvanism  ;  but  they  can  also  be  exhibited  by  powerful 
electrical  machines.      Thus   when  a  strong  charge  is  sent  through 
water,  it  is  decomposed  and  resolved  into  oxygen  and  hydrogen,  which 
immediately   assume  a  gaseous  form.     So  also  oxides  of  tin  and  mer- 
cury may  be  reduced  to  the  metallic  state. 

If  a  narrow  glass  tube  containing  chloride  of  silver  be  subjected  to  a 
series  of  electric  sparks  from  an  ordinary  machine  for  five  or  ten  min- 
utes, by  means  of  two  metallic  wires  fixed  into  the  end  of  the  tube,  the 
silver  will  be  reduced  ;  and  if  potassa  be  substituted  for  the  chloride 
of  silver,  the  potassium  will  be  seen  to  take  fire  as  it  is  produced. 

4.  Effects  upon  animals.     When  one  hand   communicates  with  the 
negative  side  of  a  charged  jar,   and  the  other  hand  is  brought  into 
contact  with  the  positive  side,  a  shock  is  observed  more  or  less  pow- 


ELECTRICITY. 

erful  according  to  the  amount  of  electricity  which  has  been  accumu- 
lated. This  shock  is  felt,  especially  at  the  joints,  for  the  reason  pro- 
bably that  the  fluid  meets  with  greater  resistance  in  passing  from  one 
bone  to  another.  When  a  shock  is  passed  through  the  muscles,  a  con- 
vulsive motion  is  produced,  even  in  those  cases  where  the  nerves  of 
a  limb  are  completely  paralyzed.  But  upon  the  nervous  system,  these 
effects  are  still  more  striking. 

The  Atmosphere  is  generally  in  an  electrical  stnte.  This  fact  can  be 
shown  by  employing  a  metallic  rod  elevated  to  some  height  above 
the  ground,  and  communicating  at  its  lower  end  with  an  electros- 
cope. Or,  if  we  wish  to  collect  electricity  from  the  higher  regions 
of  the  air,  a  kite  may  be  raised,  in  the  string  of  which  a  slender  me- 
tallic wire  should  be  interwoven,  so  as  to  conduct  the  electricity.  The 
electroscope  attached  to  this,  will  usually  show  the  prevalence  of  the 
positive  electricity,  which  increases  as  you  ascend.  This  atmospheric 
electricity,  however,  varies  in  quantity  at  different  seasons  of  the 
year,  and  at  different  times  of  the  day  ;  and  alternates  from  the  posi- 
tive to  the  negative.  Upon  the  approach  of  thunder  storms,  these 
alternations  succeed  each  other  with  great  rapidity  :  Strong  sparks  are 
given  out  by  the  conductor,  and  it  becomes  dangerous  to  prosecute 
the  experiments  with  it  in  its  insulated  state.* 

Although  the  analogy  between  the  electric  spark  and  lightning,  had 
been  a  subject  of  remark  among  the  earliest  experimenters  upon 
electricity,  it  remained  for  Dr.  Franklin  to  prove  it  directly. 
He  did  this  by  the  celebrated  experiment  of  raising  a  kite  during  a 
storm,  when  he  succeeded  in  obtaining  sparks  from  a  key  attached 
to  the  lower  end  of  the  hempen  string  of  the  kite.  This  grand  dis- 
covery excited  the  attention  of  philosophers  in  every  part  of  the 
world,  and  the  experiment  was  every  where  repeated.  It  was,  how- 
ever, in  many  instances,  attended  with  risk,  and  proved  fatal  to  Pro- 
fessor Richman,  of  St.  Petersburgh,  in  1753. 

The  most  important  practical  application  of  the  theory  of  electri- 
city, is  the  protection  of  houses,  ships,  &c.  from  the  effects  of  light- 
ning. This  is  effected  by  means  of  a  metallic  conductor,  which  is 
called  a  Lightning-rod,'  being  a  rod  of  iron  or  copper,  about  half  an 
inch  in  diameter,  the  extremity  of  which  projects  some  distance  above 
the  building,  and  is  pointed  with  silver,  platinum  or  gold,  the  more 
completely  to  preserve  it  from  corrosion.  No  interruption  should 
exist  in  the  rod,  and  the  lower  end  should  be  carried  into  the  earth  un- 
til it  reaches  water,  or  at  least  a  moist  stratum. 

REFERENCES.  Franklin's  Workf*  Library  of  Useful  Knoioledge,  art. 
Electricity.  Priestley's  History  of  Electricity.  Cavallo's  Philosophy. 
HioCs  Traife  de. Physique,  or  Cambridge  Course  of  P/iysics.  Gay  Lussac's 
instructions  respecting  Par-itonnerret,  or  Conductors  of  Lightning,  Ann. 
of  Phil.  xxiv.  4:27.  Pouillefs  Eleniens  de  Physique,  ii.  Cuthberlsoti's  Prac- 
tical Electricity  and  Galvanism. 

*  Water  rnny  be  readily  decomposed  by  atmospheric  electricity  in  the  man- 
ner proposed  by  M.  Bonijol.  The  electricity  is  gathered  by  means  of  a  very 
mie  point  fixed  at  the  extremity  of  ;m  insulated  rod  :  (he  lotte,r  is  connected 
with  the  apparatus,  in  which  the  water  is  to  be  decomposed,  by  a  metallic 
\vire,  of  which  the  diameter  does  not  exceed  l-50th  of  an  inch.  In  this  way 
the  decomposition  of  the  water  proceeds  in  a  coritii  uous  and  rapid  manner, 
notwithstanding  the  electricity  of  the  atmosphere  is  not  very  strong.  Stormy 
weather  is  quite  sufficient  for  the  purpose. — Bib.  Univ. 


GALVANISM.  77 


GALVANISM. 

The  science  of  Galvanism  owes  its  name  and  origin  to  the  experi- 
ments made  by  Galvani,  Professor  of  Anatomy  at  Bologna,  in  Italy, 
in  the  year  1790.  Being  engaged  in  some  researches  on  animal  irrita- 
bility, he  observed  that  when  a  piece  of  zinc  was  placed  in  contact 
with  the  nerve  of  a  frog,  and  a  piece  of  silver  or  copper  with  the  mus- 
cle, the  animal  was  violently  convulsed.  In  this  fact  he  conceived  that 
he  had  found  a  strong  confirmation  of  a  theory  which  he  had  adopted, 
that  the  nervous  fluid  was  somewhat  analogous  to  electricity,  and 
these  convulsions  were  consequently  ascribed  by  him  to  a  discharge  of 
this  nervous  or  electrical  energy  from  the  muscles  in  consequence  of 
the  conducting  power  of  the  metals.  And  to  this  he  gave  the  name  of 
Animal  Electricity. 

The  fallacy  of  the  notions  of  Galvani  was  first  pointed  out  by  the 
celebrated  Volta,  of  Pavia,  who  in  repeating  the  experiments,  soon  es- 
tablished the  fact  that  electricity  is  excited  by  the  contact  of  the  me- 
tals, and  that  the  convulsions  are  owing  to  the  current  passing  through 
the  conducting  muscle  and  nerve.*  And  as  it  is  to  him  we  are  in- 
debted for  the  first  true  explanation  of  this  curious  fact,  so  did  he  first 
contrive  an  apparatus  for  exciting  electricity  in  this  manner. 

The  instrument  constructed  by  Volta  for  this  purpose  was  called 
the  Pile;  a  description  of  which  was  first  published  in  the  Philosoph- 
ical Transactions,  for  1800.  It  consists  of  any  number  of  pairs  of  zinc 
and  copper,  or  zinc  and  silver,  plates,  each  pair  being  separated  from 
the  adjoining  ones  by  pieces  of  cloth,  nearly  of  the  same  size  as 
the  plates,  and  moistened  in  a  saturated  solution  of  salt.  The  relative 
position  of  the  metals  in  each  pair  must  be  the  same  in  the  whole  se- 
ries :  that  is,  if  the  copper  is  placed  below  the  zinc  in  the  first  combi- 
nation, the  same  order  must  be  preserved  in  all  the  others.  The  pile 
is  contained  in  a  proper  frame,  formed  of  glass  pillars,  fixed  into  a  piece 
of  thick  wood,  which  both  supports  and  insulates  it. 

This  form  of  the  galvanic  series,  soon  gave  place  to  the  more  con- 
venient one  of  the  Trough,  or  battery,  invented  by  Mr.  Cruickshank. 
This  consists  of  a  trough  of  baked  wood,  in  which  are  placed  at 
equal  distances,  any  number  of  zinc  and  copper  plates,  previously 
soldered  together,  and  so  arranged  that  the  same  metal  shall  always 
be  on  the  same  side.  Each  pair  is  fixed  in  a  groove  cut  in  the  sides 
and  bottom  of  the  box,  the  points  of  junction  being  made  water- 
tight by  cement.  The  apparatus  thus  constructed  is  always  ready 
for  use,  and  is  brought  into  action  by  filling  the  cells  left  between  the 
pairs  of  plates  with  some  convenient  solution,  which  serves  the  same 
purpose  as  the  moistened  cloth  in  the  pile  of  Volta. 

Several  modifications  in  the  construction  of  the  battery  were  after- 
wards proposed.  One  of  these  was  suggested  by  the  Couronne  des 
Tasses  of  Volta  ;  in  which  the  trough  made  either  of  baked  wood  or 

*  This  fact  may  be  illustrated  by  the  following  simple  experiment — Place 
a  piece  of  silver  upon  the  tongue,  and  a  piece  of  zinc  under  it ;  upon  bringing 
their  ends  into  contact  we  immediately  perceive  a  saline  taste  and  a  peculiar 
sensation  resembling  a  slight  electric  shock.  Sometimes,  also,  when  the  sur- 
face of  the  metals  is  extensive,  a  flash  of  light  appears  to  pass  before  the  eyes  ; 
an  effect  which  may  be  more  certainly  produced  by  placing  one  metal  between 
the  upper  lip  and  the  gums,  and  bringing  their  ends  together  as  before. 

P 


78  GALVANISM. 

glazed  earthen,  is  divided  into  partitions  by  the  same  material.  A 
more  important  improvement  was  suggested  by  Dr.  Wollaston,  who 
recommends  that  each  cell  should  contain  one  zinc  and  two  copper 
plates,  so  that  both  surfaces  of  the  first  metal  are  opposed  to  one  of 
the  second.  By  this  arrangement  the  plates  of  copper  communicate 
with  each  other,  and  the  zinc  between  them  with  the  copper  of  the  ad- 
joining cell.  An  increase  of  one  half  the  power  is  obtained  by  this 
method. 

The  size  and  number  of  plates  are  subject  to  every  variety.  The 
largest  battery  ever  made,  is  said  to  be  the  one  of  Mr.  Children,  the 
plates  of  which  are  six  feet  long  and  two  feet  eight  inches  broad.  [See 
Ann.  of  Phil.  vii.  11.]  The  great  battery  of  the  Royal  Institution, 
with  which  Sir  Humphry  Davy  established  the  true  nature  of  the  fixed 
alkalies  and  alkaline  earths,  is  composed  of  2000  pairs  of  plates,  each 
plate  having  32  square  inches  of  surface.  These  form  a  striking  con- 
trast to  the  elementary  battery  of  Dr.  Wollaston,  consisting  of  a  sin- 
gle pair  of  plates,  of  very  small  dimensions,  with  which  he  succeeded 
infusing  and  igniting  a  fine  platina  wire. — Ann.  of  Phil.  vi.  209. 

The  fluid  generally  used  for  rendering  these  batteries  energetic,  is 
one  of  the  stronger  acids,  diluted  with  20  or  30  times  its  weight  of 
water.  Mr.  Children  recommends  a  mixture  of  three  parts  of  fuming 
nitrous  acid,  and  one  of  sulphuric,  diluted  with  30  parts  of  water. 
Directions  also  respecting  the  kind  and  density  of  acids,  for  producing 
galvanic  electricity,  are  given  by  Mr.  Singer.  From  his  experiments 
it  appears  that  acid  of  different  densities  is  required  for  different  pur- 
poses. The  best  wire-melting  charge  is  formed  with  ten  gallons  of 
water,  five  pounds  of  nitric  acid  and  half  a  pound  of  muriatic  acid. 
According  to  Gay  Lussac  and  Thenard,  dilute  nitric  acid  is  the  best 
where  we  wish  to  produce  instantly  the  highest  energy  of  the  battery 
— while  muriatic  acid  should  be  employed  when  the  object  is  to  obtain 
a  prolonged  action. 

The  Electric  Column  may  be  classed  among  galvanic  arrangements. 
It  was  originally  contrived  by  M.  De  Luc,  who  formed  it  of  disks  of 
Dutch  gilt  paper,  alternated  with  similar  disks  of  laminated  zinc. 
These  were  piled  on  each  other  in  a  dry  state,  (or  at  least  in  a  state 
of  dryness  at  ordinary  temperatures,  for  paper  can  not  be  made  or 
preserved  absolutely  dry,  except  at  a  heat  nearly  sufficient  to  scorch 
it.)  This  instrument,  instead  of  being  soon  exhausted,  like  the  pile 
with  humid  substances,  was  found  to  continue  active  for  some  years. 
A  similar  pile  may  be  formed,  by  laying  a  mixture  of  very  finely  pow- 
dered zinc  with  common  glue  and  a  little  sugar,  by  means  of  a  brush, 
on  the  back  of  Dutch  gilt  paper,  and  when  dry,  cutting  it  into  disks, 
which  are  to  be  piled  on  each  other. — [Phil.  Mag.  xlvii.  265.]  Zam- 
boni,  of  Verona,  has  constructed  a  pile  of  slips  of  silver  paper,  on 
the  unsilvered  side  of  which  is  spread  a  layer  of  black  oxide  of  man- 
ganese and  honey.  These  papers  are  piled  on  each  other,  to  the 
number  of  2000;  then  covered  externally  with  a  coating  of  shell-lac, 
and  enclosed  in  a  hollow  brass  cylinder.  Two  of  these  piles  are 
placed  at  the  distance  of  four  or  five  inches  from  each  other  ;  and 
between  them  is  suspended,  on  a  pivot,  a  light  metallic  needle,  which 
is  attracted  alternately  to  the  one  pile  and  the  other,  so  that  it  moves 
between  them  like  a  pendulum.  This  instrument  has  been  applied 
to  the  measurement  of  time,  by  causing  it  to  give  motion  to  the  pen- 
dulum of  a  clock.— Phil.  Mag.  xiv.  261.  Henry,  i.  188. 


GALVANISM.  79 

The  more  striking  effects  of  the  voltaic  battery  may  be  reduced  to 
four  general  heads. 

I.    ITS   ELECTRICAL    PHENOMENA. 
II.    ITS    CHEMICAL    AGENCY. 

III.  ITS   POWER    OF    IGNITING   THE   METALS. 

IV.  ITS    ACTION    ON    THE    MAGNET. 

I.  Electrical  Phenomena.  Galvanism,  even  when  excited  by  a  single 
galvanic  circle  only,  (such  as  a  piece  of  zinc,  a  similar  one  of  copper, 
and  a  piece  of  cloth  moistened  with  a  solution  of  muriate  of  ammo- 
nia,) distinctly  affects  the  gold  leaf  of  Bennet's  electrometer.  If  the 
zinc  end  be  uppermost,  and  be  connected  directly  with  the  instrument, 
the  electricity  indicated  is  positive  ;  if  the  pin  of  the  electrometer 
touch  the  copper,  the  electricity  is  negative.  A  pile  consisting  of  six- 
ty combinations  produces  the  effect  still  more  remarkably.  [For  cau- 
tions necessary  to  the  success  of  this  experiment,  see  Singer,  317.] 

The  Voltaic  apparatus  is  capable  of  communicating  a  charge  to  a 
Leyden  jar,  or  even  to  a  battery.  If  the  zinc  end  of  a  pile  be  made  to 
communicate,  for  a  moment,  with  the  inside  of  a  jar,  it  is  charged 
positively.  If  the  circumstances  be  reversed,  the  jar  is  charged  nega- 
tively.—  Cuthbertsori 's  Practical  Electricity  and  Galvanism,  261. 

The  sensation  produced  by  the  galvanic  shock  is  extremely  similar 
to  that  which  is  excited  by  the  discharge  of  a  Leyden  jar.  Both  in- 
fluences, also,  are  propagated  through  a  number  of  persons,  without 
any  perceptible  interval  of  time. 

The  galvanic  fluid  passes  through  the  air,  and  certain  other  non- 
conductors, in  the  form  of  sparks  ;  accompanied  with  a  snap  or  re- 
port ;  and,  like  the  electrical  fluid,  it  may  be  made  to  inflame  gun- 
powder, phosphorus,  and  mixtures  of  hydrogen  and  ox v  gen  gases.  It 
has  been  found,  also,  by  Mr.  Children,  that  in  the  voltaic  apparatus, 
there  is  what  is  called  in  electricity,  a  striking  distance.  With  a  power 
of  1250  pairs  of  four  inch  plates,  he  found  this  distance  to  be  one  50th 
of  an  inch,  the  thickness  of  a  plate  of  air,  through  which  the  galvanic 
discharge  is  able  to  pass  in  the  form  of  a  spark.  By  increasing  the 
number  of  plates,  the  striking  distance  will  be  greater,  and  the  reverse 
when  it  is  diminished.  It  is  also  increased  by  rarifying  the  air, 
through  which  the  spark  is  transmitted. — See  Henry's  Chemistry  on  the 
mutual  relations  of  Electricity  and  Galvanism,  i.  189. 

For  the  purpose  of  exhibiting  the  effects  just  mentioned,  a  number 
of  plates  is  necessary,  without  reference  to  the  size.  Acid  solutions 
are  to  be  preferred  when  shocks  or  sparks  are  required  ;  water  is  pre- 
ferable for  effecting  the  electrometer  or  Leyden  jar. 

II.  Chemical  effects  of  the  battery.  The  chemical  effect  of  the  bat- 
tery first  noticed,  was  the  decomposition  of  water,  which,  as  we  shall 
hereafter  see,  is  a  compound  of  oxygen  and  hydrogen. 

When  two  gold  or  platinum  wires  are  connected  with  the  opposite 
poles  of  a  battery,  and  their  free  ends  plunged  into  the  same  cup  of 
water,  but  without  touching  each  other,  oxygen  gas  is  disengaged  at 
the  positive  wire,  and  hydrogen  gas  at  the  negative.  These  gases 
may  be  collected  at  separate  tubes,  or  in  a  single  bent  tube,  and  sub- 
jected to  experiment.  [See  a  very  simple  apparatus  for  collecting  the 
gases  evolved  from  liquids  submitted  to  galvanic  action,  by  the  Rev.  Mr. 
Robertson,  in  Edin.  New  Phil.  Jour.  iii.  44.]  If,  however,  we  em- 
ploy wires  of  copper,  silver,  or  any  other  oxidable  metal,  the  oxygen 


80  GALVANISM. 

no  longer  appears  in  the  form  of  gas,  but  unites  with  the  wire,  and 
oxidates  it. 

If,  instead  of  water,  we  subject  to  the  action  of  the  poles  of  the 
battery,  acids  or  saline  solutions,  they  are,  in  like  manner,  decomposed; 
one  of  their  elements  appearing  at  one  pole  and  the  other  at  the 
other.  There  is  an  exact  uniformity  in  the  circumstances  attending 
these  decompositions.  Thus,  in  decomposing  water  or  other  com- 
pounds, the  same  kind  of  body  is  always  disengaged  at  the  same  pole 
of  the  battery.  The  metals,  inflammable  substances  in  general,  the 
alkalies,  earths,  and  the  oxides  of  the  common  metals,  are  found  at 
the  negative  pole  ;  while  oxygen,  chlorine,  and  the  acids  pass  over  to 
the  positive  end. 

If  the  conducting  wires  are  plunged  into  separate  vessels  of  water, 
and  made  to  communicate  with  each  other  by  moist  fibres  of  cotton  or 
amianthus,  the  two  gases  are  still  disengaged  in  the  usual  order.  And 
if  one  vessel  containing  a  neutral  salt,  (sulphate  of  soda  for  example,) 
communicates  with  the  negative  pole,  and  another  containing  dis- 
tilled water  with  the  positive,  and  the  two  cups  be  united  by  moisten-  ' 
ed  amianthus,  the  acid  of  the  salt  passes  over  to  the  water,  and  the 
salt  becomes  distinctly  alkaline.  On  reversing  the  pole,  the  alkali 
passes  over  to  the  water,  and  the  saline  solution  becomes  distinctly 
acid.  These  singular  results  were  first  obtained  by  Sir  H.  Davy,  and 
described  by  him  in  the  Phil.  Trans,  for  1807. 

The  same  results  will  still  be  observed,  though  a  cup  of  ammonia 
intervene  between  those  of  distilled  water  and  the  saline  solution  ; 
from  which  it  appears  that  the  galvanic  action  not  only  separates  the 
elements  of  compound  bodies,  but  suspends  the  operation  of  affinity  so 
entirely  as  to  enable  an  acid  to  pass  through  an  alkaline  solution,  or 
an  alkali  through  water  containing  a  free  acid,  without  combination 
taking  place  between  them.  The  three  cups  being  arranged  as  in  the 
last  experiment,  Sir  H.  Davy  put  a  solution  of  sulphate  of  potassa  in 
one,  pure  water  in  another,  and  a  weak  solution  of  ammonia  in  the 
intermediate  cup,  so  that  no  sulphuric  acid  could  find  its  way  to  the 
distilled  water,  without  passing  through  the  ammoniacal  liquid  in  its 
passage.  A  battery,  composed  of  150  pairs  of  4-inch  plates,  was  set 
in  action,  and  in  five  minutes,  free  acid  appeared  at  the  positive  pole. 
Muriatic  and  nitric  acids  were,  in  like  manner,  made  to  pass  through 
strong  alkaline  solutions  ;  and  on  reversing  the  experiment,  alkalies 
were  transmitted  directly  through  acid  liquids  without  entering  into 
combination  with  them. 

It  has  been  shown,  in  our  remarks  upon  electricity,  that  bodies 
which  are  similarly  electrified  repel  each  other,  while  those  which  are 
dissimilarly  electrified  attract  each  other.  Now  the  invariable  ten- 
dency of  oxygen  and  the  acids  to  the  positive  pole  of  the  battery  and  of 
hydrogen  and  the  alkalies  to  the  negative,  can  only  be  explained  upon 
the  principle  that  the  former  are  negatively,  and  the  latter  positively 
electrified  at  the  moment  of  their  separation  from  each  other.  This 
forms  the  basis  of  the  hypothesis  advanced  by  Davy,  which  has  re- 
ceived the  appellation  of  the  Electro  Chemical  Theory,  and  has  been 
adopted  by  several  philosophers,  especially  by  Berzelius. 

It  has  been  shown  by  Volta  that  when  two  metals  are  brought  into 
contact,  they  are,  on  being  separated,  in  opposite  electrical  states. 
Thus,  when  an  insulated  plate  of  zinc  is  brought  into  contact  with 
one  of  silver  or  copper,  the  former  is  found  to  be  in  a  positive  state, 
and  the  latter  negative.  Sir  H.  Davy  also  ascertained  that  a  similar 
effect  is  produced  by  the  contact  of  other  bodies.  A  dry  alkali  or  an  al- 


GALVANISM.  81 

kaline  earth,  for  example,  is  excited  positively  by  contact  with  a  me- 
tal ;  dry  acids  after  having  touched  a  metal  are  negative,  and  the  con- 
tact of  acids  and  alkalies,  in  their  dry  state,  render  the  former  negative 
and  the  latter  positive.  He  further  observed  that  electrical  effects  are 
exhibited  by  the  same  bodies,  when  acting  as  masses,  which  produce 
chemical  phenomena  when  acting  by  their  particles,  or  atoms.  It  is, 
therefore,  by  no  means  improbable,  that  the  primary  cause  of  both 
these  phenomena  maybe  the  same,  and  that  the  same  arrangements  of 
matter  which  render  bodies  attractive  of  each  other  electrically,  may 
likewise  render  their  particles  attractive,  and  enable  them  to  combine, 
when  they  have  full  freedom  of  motion. 

According  to  the  above  view,  all  substances  which  have  a  chemical 
affinity  for  each  other,  are  in  different  states  of  electricity,  and  the  de- 
gree of  affinity  is  proportional  to  the  intensity  of  these  opposite  states. 
When  such  a  compound  body  is  placed  in  contact  with  the  poles  of  a 
Voltaic  battery,  the  positive  pole  attracts  the  constituent  which  is 
negative,  and  repels  the  positive.  The  negative  acts  in  the  opposite 
way,  attracting  the  positive  constituent  and  repelling  the  negative. 
Thus,  when  water  is  subjected  to  the  action  of  the  battery,  its  oxygen 
invariably  appears  at  the  positive  pole,  and  its  hydrogen  at  the  nega- 
tive. Hence  hydrogen  and  all  other  substances  which  like  it  are  at- 
tracted by  the  negative  pole,  are  classed  together  as  electro-positive 
bodies ;  and  oxygen  and  other  substances  which  are  attracted  by  the 
positive  pole  are  called  electro -negative  bodies. 

In  following  out  these  ideas,  Davy  conceived  that  no  compound  could 
resist  decomposition,  if  subjected  to  the  action  of  a  battery  of  sufficient 
power.  He  accordingly  exposed  to  galvanic  action  substances,  which, 
although  they  had  been  thought  to  be  compound,  had  baffled  all  at- 
tempts to  analyze  them.  The  result  was  successful.  Potash  was" 
proved  to  consist  of  a  metallic  basis  in  combination  with  oxygen,  and 
continuing  his  investigations,  he  soon  decomposed  the  other  fixed  alka- 
lies and  alkaline  earths,  and  rendered  it  almost  certain  that  the  earths 
proper  were  similarly  constituted. 

Although  some  of  the  conditions  of  the  Electro-Chemical  Theory 
have  not  yet  been  demonstrated,  yet  it  rests  on  extensive  observation  and 
is  supported  by  numerous  facts.  It  affords  also  the  most  easy  expla- 
nation of  the  phenomena  ascribed  to  affinity.  It  appears  to  me,  more- 
over, to  furnish  principles  the  most  philosophical  for  the  arrangement 
of  chemical  substances,  and  on  this  account  I  shall  follow  the  example 
of  Mr.  Brande  and  Dr.  Henry,  and  treat  of  individual  substances  in 
the  order  of  their  electrical  relations. 

III.  The,  igniting  effects  of  the  battery.  The  ignition  of  the  metals 
seems  to  depend  upon  the  difficulty  with  which  electricity  passes  along 
them.  But  as  they  are  perfect  conductors,  this  can  only  take  place 
when  the  quantity  to  be  transmitted  is  out  of  proportion  to  the  extent 
of  surface  along  which  it  has  to  pass.  For  this  purpose,  therefore,  it 
is  important  to  excite  as  large  a  quantity  of  electricity  in  a  given  time 
as  possible  ;  and  hence  a  few  large  plates  answer  a  better  purpose  than 
a  number  of  small  ones.  A  strong  acid  solution  should  also  be  used, 
as  an  energetic  action  is  more  important  than  its  permanence. 

With  regard  to  the  powers  of  the  Voltaic  series  in  igniting  the  met- 
als, a  very  important  improvement  has  been  made  by  Dr.  Hare,  of 
Philadelphia.  This  was  suggested  by  a  notice  of  the  fact,  that  the 
igniting  power  of  the  battery  attains  its  highest  intensity  almost  as 
soon  as  the  plates  are  covered  with  the  acid  used  to  excite  them.  It 


82  GALVANISM. 

must  be  evident  therefore,  that  a  large  battery  constructed  in  the  or- 
dinary way,  must  lose  much  of  its  power  before  it  can  be  used. 

In  the  apparatus  of  Dr.  Hare,  as  at  present  constructed,  the  metals 
are  fixed  in  a  box,  which  is  made  to  revolve  on  pivots,  and  thus  by  a 
quarter  revolution,  the  acid  is  thrown  entirely  off  into  another  box, 
attached  at  right  angles  to  the  first,  and  by  reversing  the  revolution  at 
pleasure,  the  acid  returns  upon  the  plates.  This  instrument  is  named 
by  the  inventor,  a  Galvanic  Deflfigrator,  and  where  the  igniting  effects  are 
required  to  be  exhibited,  it  possesses  advantages  over  every  other  form  of 
the  galvanic  apparatus  hitherto  discovered.  The  metals  are  readily 
fused  by  it,  and  it  produces  a  vivid  ignition  in  charcoal,  and  when  the 
points  of  the  charcoal  are  drawn  three-fourths  of  an  inch  apart,  a  most 
brilliant  arc  of  flame  extends  between  them. 

It  should  be  remarked,  that  Dr.  Hare  is  opposed  to  the  opinion  above 
stated,  concerning  the  heat  produced  by  galvanic  combinations.  He 
supposes  that  heat,  like  electricity,  is  an  original  product  of  galvanic 
action.  According  to  his  views,  the  relative  proportion  of  the  two 
principles  evolved,  depends  upon  the  construction  of  the  apparatus, 
the  caloric  being  in  proportion  to  the  extent  of  the  generating  surface, 
and  the  electricity  to  the  number  of  the  series.  In  the  case  of  batteries, 
in  which  the  size  and  number  of  the  plates  are  very  considerable,  both 
electricity  and  caloric  are  presumed  by  him  to  be  generated  in  large 
quantities.  When  the  number  of  the  plates  is  very  great,  and  their 
size  insignificant,  as  in  De  Luc's  column,  electricity  is  the  sole  pro- 
duct ;  and  conversely,  where  the  size  is  very  great  and  the  number  of 
the  series  small,  caloric  is  abundantly  produced,  and  the  electrical 
effects  are  nearly  null. — [Fora  full  account  of  the  theory  of  Dr.  Hare, 
see  Sittiman's  Jour.  i.  413.] 

IV.  The  action  on  the  magnet.  This  interesting  subject  will  be  no- 
ticed in  connection  with  the  general  view  of  the  laws  of  magnetism,  in 
the  next  chapter. 

THEORIES    OF    GALVANISM. 

There  are  three  leading  theories  which  have  been  constructed  to  ac- 
count for  the  phenomena  of  the  galvanic  pile,  and  of  all  similar  ar- 
rangements. The  first  originated  with  Volta,  who  maintained,  that 
the  electricity  was  set  in  motion  and  kept  up  solely  by  the  contact 
of  the  metals.  But  as  no  very  sensible  effects  are  produced,  un- 
less the  substances  employed  have  a  chemical  action  on  each  other, 
Dr.  Wollaston  was  led  to  conclude,  that  the  process  commences 
with  the  oxidation  of  the  zinc,  and  that  the  oxidation  is  the  pri- 
mary cause  of  the  developement  of  electricity.  The  theory  of  Davy 
is  intermediate  between  the  two  just  mentioned,  and  is  perhaps 
most  conformable  to  the  facts  hitherto  discovered.  He  supposes  that 
the  contact  of  the  metals  disturbs  the  electric  equilibrium,  and  that 
the  electric  action  is  afterwards  kept  up  by  the  action  of  the  solution 
upon  the  zinc.  But  in  the  present  state  of  the  science,  neither  of  these 
theories  appears  to  be  altogether  satisfactory.  The  reader  who  wishes 
to  examine  them  more  in  detail,  is  referred  to  Bostoch's  Remarks  on  the, 
Hypotheses  of  Galvanism,  in  Ann.  of  Phil.  iii.  32,  85.  Sir  H.  Davy's 
chapter  on  Electrical  Attraction  and  Repulsion,  in  his  Chem,  Phil.  ;  and 
Gay  Lussac  and  Thenard's  Rccherches. 


MAGNETISM.  83 

REFERENCES.  Cuthbertsorfs  Practical  Electricity  and  Galvanism.  Sin- 
ger on  Electricity  and  Galvanism.  Several  papers  by  Volta,  Singer,  De 
Luc,  and  Henry,  in  Nicholson's  Journal.  Library  of  Useful  Knowledge, 
Art.  Galvanism,  by  Dr.  Roget.  Davy  on  the  Chemical  Agencies  of  Electri- 
city, Phil.  Trans.  1807  and  1826,  and  also  Phil.  Mag.  and  Ann.  i.  Oersted 
on  the  Identity  of  Chemical  and  Electrical  Forces,  Ann.  of  Phil.  xiii.  369, 
456,  xiv.  47.  Thomson  on  Heat  and  Electridty.  The  first  eight  volumes 
of  Silliman's  Journal  contain  sundry  papers  by  Professors  Hare  and  Silli- 
man,  upon  Calorinwtors,  Dejlagrators,  fyc. 


CHAPTER  V. 

MAGNETISM. 

Though  the  consideration  of  Magnetism  belongs,  strictly  to  the  de- 
partment of  natural  philosophy,  I  shall  advert  briefly  to  its  more  pro- 
minent laws,  as  by  this  means  the  reader  will  be  better  prepared  to 
understand  the  facts  of  Electro-Magnetism. 

Most  of  the  fragments  of  iron  ore  in  which  a  degree  of  oxidation 
has  taken  place,  are  found  to  possess,  when  taken  from  the  earth,  the 
singular  property  of  attracting  particles  of  iron,  by  an  invisible  power. 
The  force  of  this  attraction  is  sometimes  so  powerful  as  to  raise  con- 
siderable weights.  This  mineral  has  received  the  name  of  a  magnet, 
from  the  Greek  word  magnees  ;  and  hence  the  term  magnetism  is  used 
to  stand  for  the  phenomena  exhibited  by  this  mineral ; — in  the  same 
way  that  the  term  electricity  is  applied  to  the  unknown  cause  of  elec- 
trical phenomena.  This  influence  may  be  communicated  to  some  me- 
tallic bodies,  and  particularly  to  iron  and  steel. 

When  a  magnet  is  rolled  in  iron  filings,  different  quantities  of  the 
filings  are  attached  to  different  parts  of  its  surface.  This  effect  is 
particularly  sensible  at  two  opposite  points,  where  the  filings  are  ac- 
cumulated in  the  greatest  abundance,  standing  as  it  were  on  end, 
nearly  parallel  to  each  other.  These  parts  are  called  the  poles  of  the 
magnet. 

When  a  magnet  is  suspended  horizontally  by  an  untwisted  thread, 
or  bundle  of  silk  fibres,  or  when  it  is  made  to  float  on  water,  it  takes  a 
determinate  direction.  This  direction,  however,  differs  in  different 
parts  of  the  earth,  being  in  some  exactly  in  the  meridian,  in  others,  in- 
clining towards  the  west ;  and  in  others  again,  towards  the  east. 

If  to  one  of  the  poles  of  a  magnet  thus  suspended,  a  similar  pole  of 
another  magnet  be  presented,  they  will  repel  each  other  ;  but  if  the 
opposite  poles  are  presented,  they  will  attract  each  other.  This  is 
analogous  to  what  takes  place  when  bodies  are  under  the  influence 
of  electricity ,  and  hence  similar  laws  of  attraction  and  repulsion  are 
applicable. 

To  these  poles,  the  names  of  north  and  south,  or  boreal  and  austral, 
have  been  applied  ;  and  by  Berzelius,  positive  and  negative. — Traite  de 
Chim.  i.  170. 

When  a  steel  bar  is  suspended  freely  by  its  centre  of  gravity,  and 
afterwards  carefully  magnetized,  it  will  be  found  not  only  to  place 
itself  in  the  magnetic  meridian,  but  to  assume  a  position  inclined  to  the 


84  .  MAGNETISM. 

horizon.  In  northern  latitudes,  the  northern  pole  of  the  needle  will 
incline  beneath  the  horizontal  plane,  and  the  other  will  be  raised 
above  it.  This  angle  of  inclination  varies  but  little  at  the  same  place, 
and  is  called  the  dip  of  the  needle.  There  is  a  zone  not  far  from  the 
equator,  where  the  magnet  hangs  in  a  horizontal  position  ;  to  the 
south  of  this  the  northern  pole  will  be  elevated,  and  the  southern  will 
dip. 

Although  the  magnet  exerts  its  force  at  the  distance  of  several  feet, 
it  decreases  in  strength  as  the  distances  increase,  but  in  very  different 
ratios  in  different  magnets.  In  some  the  force  of  attraction  seems  to 
be  inversely  as  the  square  of  the  distances  ;  in  others  as  the  cubes  of 
the  distances ;  and  so  on  in  other  proportions.  Its  virtue  is  exerted  in 
vacua,  as  well  as  in  open  air,  and  without  any  sensible  diminution  of 
its  force  by  the  interposition  of  the  hardest  bodies,  whose  pores  it  easi- 
ly pervades. 

*  The  magnetic  property  is  found  also  to  reside  naturally  in  nickel 
and  a  few  other  metals.  It  may  be  communicated  to  iron  and  steel,  as 
follows  : 

1.  By  the  contact  of  a  natural  magnet.     This  is  indeed  proved  by 
examining  the  crest  of  iron  filings  attached  to  the  poles  of  the  magnet, 
which  will  be  found  to  consist  of  several  minute  magnets  adhering  end 
to  end. 

Bars  of  soft  iron  may  be  rendered  quickly  magnetic  by  the  contact 
of  a  magnet.  Thus,  if  we  suspend  a  small  bar  of  soft  iron  to  the  pole 
of  a  magnet,  the  lower  end  will  immediately  acquire  all  the  magnetic 
properties.  A  second  and  a  third  bar  added  to  this  will  adhere  to  one 
another,  until  their  total  weight  exceeds  that  which  themagnet  is  capa- 
ble of  supporting.  When  the  first  bar  detaches  itself  they  all  fall,  and 
lose,  in  a  great  measure,  their  magnetic  powers. 

Bars  of  steel  may  also  be  magnetized  by  the  contact  of  a  magnet  or 
magnets,  but  this  is  effected  with  more  difficulty  ;  though  the  bars  re- 
tain magnetism  much  longer.  The  same  magnet  may  thus  successive- 
ly magnetize  any  number  of  steel  bars,  without  losing  any  portion  of 
its  original  virtue,  if  the  bars  be  not  too  large  ;  from  which  it  follows 
that  the  magnet  communicates  nothing  to  the  bars,  but  only  developes, 
by  its  influence,  some  hidden  principle.  [For  details  of  the  methods 
of  magnetizing  bars  of  steel,  see  Blot's  Traite  Precis,  or  Cambridge 
Course  of  Physics.] 

2.  Besides  the  contact  of  a  magnet,  magnetism  may  be  communi- 
cated to  iron  and  steel  by  placing  them  in  the  magnetic  meridian — by 
torsion  or  twisting — by  the  blow  of  a  hammer — by  pressure — by  the  act 
of  rotation — and  even,   as  some  have  supposed,  by  mere  exposure  to 
certain  rays  of  light.     [See  p.  69.] 

The  directive  power  of  the  magnet  is  the  most  important  property 
which  it  possesses  ;  and  it  is  this  which  has  led  to  the  construction  of 
the  Compass,  an  instrument  wherein  a  magnetized  needle  is  employed, 
to  ascertain  the  direction  of  objects  from  the  point  in  which  it  is  placed. 
It  is  more  especially  useful  in  pointing  out  the  course  of  a  vessel  when 
at  sea,  and  out  of  sight  of  land :  without  this  valuable  invention,  it 
would  have  been  out  of  our  power  to  have  traversed  the  great  oceans, 
that  form  so  large  a  portion  of  the  globe. 

The  directive  force  of  the  needle  is  impaired  by  the  vicinity  of  large 
masses  of  iron.  In  ships  this  is  a  source  of  much  inconvenience,  espe- 
cially in  high  northern  or  southern  latitudes.  To  remedy  the  errors 
of  the  needle,  resulting  from  this  cause,  Professor  Barlow  contrived  an 
instrument,  which  is  called  the  correcting  plate ;  the  utility  of  which, 


MAGNETISM.  85 

has  been  abundantly  proved  by  Capts.  Sabine,  Parry,  and  other  distin- 
guished naval  officers. 

Electricity  also  has  the  effect  of  varying  the  directive  power  of  the 
needle,  and  that  not  only  when  accumulated,  but  as  excited  by  the 
mere  friction  upon  the  glass  cover  of  the  compass.  Hence  needles  are 
in  this  manner  very  frequently  injured.  [See  Lieut.  E.  J.  Johnson's 
valuable  observations  on  local  and  electrical  influences  on  compasses 
variously  constructed,  in  Brande's  Jour.  xxi.  274.] 

There  are  several  practical  applications  of  the  laws  of  magnetism. 
Among  these  may  be  mentioned,  the  separation  of  iron  filings  from 
the  particles  of  sand  and  other  substances  with  which  they  are  often 
mixed.  A  neat  apparatus  for  effecting  this  object  is  described  in  the 
28th  volume  of  the  Transactions  of  the  London  Society  of  Arts.  The 
same  principle  has  also  been  applied  to  the  separation  of  the  magnetic 
ores  of  iron  from  silex,  pyrites,  and  other  substances  which  interfere 
with  the  process  of  smelting.  A  method  was  patented  in  England  in 
1792,  which  consisted  in  reducing  the  crude  ore  to  a  coarse  powder  by 
means  of  hammers,  rollers,  &c.,  and  of  separating  the  metallic  parti- 
cles by  the  employment  of  magnetic  attraction.  [Repert.  of  .Arts,  1st 
Ser.  1.]  An  American  patent  has  also  been  issued  for  a  similar  appli- 
cation of  this  principle,  which  cannot  fail  to  be  useful  in  those  districts 
where  the  magnetic  ores  of  iron  are  abundant. 

Another  beautiful  application  of  the  laws  of  magnetism,  is  the  con- 
struction of  masks  of  magnetized  steel  wire,  which  are  now  employed 
by  the  workmen  who  are  engaged  in  the  pointing  of  needles  ;  an  oc- 
cupation which  was  formerly  attended  with  great  hazard,  in  conse- 
quence of  the  fine  particles  of  steel,  continually  flying  off  from  the 
grindstones,  being  inhaled  into  the  lungs. 

Magnetism  is  also  employed  in  certain  analyses.  The  method  of 
oscillations  suggested  by  Coulomb,  is  one  of  the  most  accurate  for  as- 
certaining the  presence  of  iron,  either  in  natural  or  artificial  products. 
We  have  only  to  form  needles  of  the  substances  to  be  examined,  and 
to  make  them  oscillate  between  two  powerful  magnets,  and  to  compare 
their  oscillations  with  those  of  needles  made  of  iron,  combined  with 
some  other  substance  not  magnetic,  the  relative  proportions  of  the  iron 
and  the  unmagnetic  substance  being  known. 

It  only  remains  to  add  to  this  sketch,  a  few  words  concerning  Ter- 
restrial Magnetism. 

The  earth  may  be  considered  as  a  great  natural  magnet,  and  many 
of  the  phenomena  which  we  have  noticed  are  due  to  the  power  of  this 
magnet.  From  the  experiments  which  have  been  made  upon  the 
earth's  magnetism,  it  results  that  there  is  a  line  (called  the  magnetic 
equator,}  in  which  the  needle  has  no  dip  f  that  as  we  proceed  from  this 
line,  north  or  south,  the  dip  constantly  increases  until  we  arrive  at 
points  where  the  needle  is  vertical,  which  are  called  the  poles — that 
there  are  also  lines  which  cut  the  magnetic  equator,  in  which  the  nee- 
dle has  no  declination,  or  points  to  the  true  north  and  south. 

The  earth,  therefore,  is  a  great  natural  magnet,  with  poles  and  a 
point  where  the  influence  of  the  poles  is  exactly  balanced  ;  hence  the 
directive  power  and  the  dip  of  the  needle  are  due  to  its  influence. 

It  may  be  remarked,  that  although  the  phenomena  of  magnetism 
are  manifest  only  in  a  few  substances,  Professor  Hansteen  has  drawn 
from  numerous  experiments  and  observations,  the  important  conclu- 
sion, that  every  vertical  object,  of  w/iatever  material  it  is  composed,  has  a 
magnetic  south  pole  above,  and  a  north  pole  below. — Edin.  Phil.  Jour,  for 
1826. 


86  ELECTRO-MAGNETISM. 

REFERENCES.  Biot,  and  Cambridge  Course  of  Physics.  Renwick's  Out- 
lines of  Natural  Philosophy.  Hobisorfs  Nat.  Phil  Cavallo's  Philosophy. 
For  an  account  of  the  Experiments  on  the  peculiar  magnetic  effect  induced  in 
Iron,  and  on  the  magnetism  manifested  in  other  Metals,  fyc.  during  the  act  of 
rotation,  by  Messrs.  Barlow,  Christie,  Babbage  and  Herschel,  See  Phil. 
Trans,  for  1825.  Also,  Ann.  of  Phil,  xxvii.  and  xxviii.  Capt.  Kater^s  val- 
uable directions  for  constructing  Compass  Needles,  Ann.  of  Phil,  xviii.  231. 
For  a  description  of  Barlow's  Correcting  Plate,  see  his  Essay  on  Magnetic 
Attraction,  and  the  value  of  this  Apparatus  attested  by  Capt.  Parry,  3d 
voyage,  65  and  67,  Amer.  Ed.  Professor  Hansteerfs  Table  of  the  variations 
of  the  Magnetic  Needle,  Breioster's  Edin.  Jour.  ix.  264. — This  Journal  also 
contains  several  other  papers  by  the  same  author.  Capt.  Sabine,  on  the  Mag- 
netism of  the  Earth,  Siliiman's  Jour.  xvii.  145. 

ELECTRO-MAGNETISM. 

It  has  already  been  observed,  that  electricity,  as  developed  by  fric- 
tion, has  an  effect  upon  the  directive  power  of  the  needle.  The  pow- 
er of  lightning  also,  in  destroying  and  reversing  the  poles  of  a  magnet, 
and  in  giving  magnetic  polarity  to  pieces  of  iron  which  did  not  pre- 
viously possess  it,  has  long  been  known.  Attempts  were  accordingly 
made  at  different  times  to  communicate  the  magnetic  virtue  by  means 
of  electricity*  or  galvanism  ;  but  no  results  of  importance  were  ob- 
tained until  the  year  1819,  when  Professor  Oersted  made  his  celebra- 
ted discovery,  which  constitutes  the  basis  of  the  science  of  Electro- 
Magnetism  or  Electro-Dynamics. 

The  fact  observed  by  Professor  Oersted  was,  that  an  electric  cur- 
rent, such  as  is  supposed  to  pass  from  the  positive  to  the  negative  pole 
of  a  Voltaic  battery  along  a  wire  which  connects  them,  causes  a  mag- 
netic needle  placed  near  it  to  deviate  from  its  natural  position,  and  as- 
sume a  new  one,  the  direction  of  which  depends  upon  the  relative  po- 
sition of  the  needle  and  the  wire.  On  placing  the  wire  above  the 
magnet  and  parallel  to  it,  the  pole  next  the  negative  end  of  the  battery 
always  moves  westward,  and  when  the  wire  is  placed  under  the  needle, 
the  same  pole  goes  towards  the  east.  If  the  wire  is  on  the  same  hori- 
zontal plane  with  the  needle,  no  declination  whatever  takes  place  ;  but 
the  magnet  shows  a  disposition  to  move  in  a  vertical  direction,  the 
pole  next  the  negative  side  of  the  battery  being  depressed  when  the 
wire  is  to  the  west  of  it,  and  elevated  when  it  is  placed  on  the  east 
side,  t 


*  In  a  paper  published  by  Dr.  Franklin  in  1750,  he  observes,  **  By  electri- 
city we  have  (here  at  Philadelphia)  frequently  given  polarity  to  needles,  and 
reversed  it  at  pleasure."  "  A  shock  from  four  large  glass  jars,  sent  through  a 
fiae  sewing  needle,  gives  it  polarity,  and  it  will  traverse  when  laid  on  water. 
If  the  needle,  when  struck,  lies  east  and  west,  the  end  entered  by  the  electric 
blast  points  north.  If  it  lies  north  and  south,  the  end  that  lay  towards  the 
north  will  continue  to  point  north  when  placed  on  water,  whether  the  fire 
entered  at  that  end,  or  at  the  contrary  end.'' — Franklin's  Works,  iii.  65. 

f  This  term  is  synonymous  with  the  terms,  connecting  and  communicating 
wire,  employed  by  some  authors.  There  can  be  no  confusion  in  regard  to 
them,  when  it  is  remembered  that  the  phenomena  of  electro-magnetism  are 
solely  produced  by  electricity  in  motion.  Whatever,  therefore,  forms  the 
union  between  the  zinc  and  copper  plates  used  to  exhibit  these  effects,  is,  for 
convenience,  called  the  conjunctive  or  connecting  wire. 


ELECTRO-MAGNETISM.  87 

The  conjunctive  wire  connecting  the  two  poles  of  the  battery,  may 
consist  of  any  metal ;  even  a  tube  filled  with  mercury  is  effectual :  the 
only  difference  is,  in  the  amount  of  effect  produced.  It  continues  also, 
though  the  conductor  be  interrupted  by  water,  unless  the  interruption 
be  of  great  extent.  The  influence  of  the  wire  extends  through  all 
substances,  and  acts  upon  the  needle  beyond,  just  as  with  common 
magnetism. 

Those  forms  of  the  Voltaic  apparatus  which  generate  quantity,  are  such 
as  produce  the  most  decided  electro-magnetic  effects  ; — they  appear  to 
be  independfcit  of  tension,  and  hence  a  single  pair  of  very  large  plates, 
is  more  effectual  than  a  number  of  small  ones.  Batteries  constructed 
of  one  or  a  few  pairs  of  large  plates,  have  hence  been  called  magnet- 
omotors. 

I  shall  present  an  outline  of  the  principal  facts  of  electro-magnetism 
under  the  following  heads,  viz. 

1.  Action  of  the  conjunctive  wire  upon  the  magnet. 

2.  Action  of  the  conjunctive  wire  upon  soft  iron  and  steel. 

3.  Action  of  two  conjunctive  wires  upon  each  other. 

4.  Action  of  the  electro-  and  steel  magnet  upon  the  conjunctive  wire. 

5.  Action  of  the  earth's  magnetism  upon  the  conjunctive  wire. 

I.  Action  of  the  conjunctive  wire  upon  the  magnets. — It  has  already 
been  observed,  that  when  a  wire  connects  the  opposite  poles  of  a 
Voltaic  battery,  a  magnetic  needle  placed  near  it  is  made  to  deviate 
from  its  natural  position.  These  facts,  discovered  by  Oersted,  have 
been  confirmed  by  the  experiments  of  various  other  philosophers. 
It  has  also  been  shown  by  Ampere,  that  the  pile  itself  acts  in  the 
same  manner  as  the  conjunctive  wire,  and  his  views  of  the  phenom- 
ena led  him  to  the  construction  of  an  instrument  which,  at  the 
same  time  that  it  proved  this  action,  was  shown  to  be  of  great  value 
in  experiments  on  currents  of  electricity.  This  was  merely  a  magnetic 
needle,  but  from  the  uses  to  which  it  was  applied  was  called  a  Galvan- 
ometer. When  placed  near  a  pile  or  trough,  in  action,  having  its  poles 
connected  either  by  a  wire,  or  by  introducing  them  into  one  cell,  it 
immediately  moved,  becoming  obedient  to  the  battery,  in  the  same 
manner  as  to  the  connecting  wire  :  and  the  motions  were  such  as  if 
the  battery  were  simply  a  continuation  or  part  of  the  wire. 

The  action  of  the  conjunctive  wire  upon  the  magnet,  can  be 
more  advantageously  exhibited  by  the  instrument  invented  by  Pro- 
fesser  Schweigger,  of  Halle,  and  called  the  Electro -Magnetic  Mul- 
tiplier. This  instrument  consists  of  brass  wire,  wound  with  silk,  so 
as  to  prevent  the  electricity  from  passing  laterally,  and  wound  upon 
the  hand  or  a  book,  fifty,  or  an  hundred  or  more  times ;  the  delicacy 
of  the  apparatus  being  in  proportion  to  the  number  of  turns. — 
These  are  now  held  in  their  place  by  threads  of  silk,  and  the  two  ends 
of  the  wire  are  left  free.  We  have  thus  an  oval  bundle  of  wires, 
through  which,  when  the  ends  are  connected  with  an  active  battery, 
the  current  of  electricity  passes.  If  now  we  place  a  freely  suspended 
magnetic  needle  in  the  middle  of  this  oval  multiplier,  and  then 
connect  the  two  ends  of  the  wires  with  the  two  opposite  poles  of  a 
battery,  the  needle,  after  several  oscillations,  becomes  stationary  at 
right  angles  to  the  oval,  the  influence  of  terrestrial  magnetism  being 
surmounted  by  that  of  the  multiplier.  When  this  instrument  con- 
sists of  60  or  100  turns,  the  needle  may  be  made  to  deviate  by  disks  of 
zinc  and  copper,  an  inch  in  diameter,  and  merely  united  by  paper, 


88  ELECTRO-MAGNETISM. 

moistened  by  any  saline  solution,  or  even  by  saliva. — See  Ann.  of  Phil. 
xxi.  436. 

Various  modifications  of  this  apparatus  have  been  proposed  ;  that 
invented  by  Professor  Henry  and  described  by  him  in  the  first  volume 
of  the  Transactions  of  the  Albany  Institute,  is  one  of  the  most  con- 
venient. 

It  appears  therefore,  that  the  wire  connecting  the  two  opposite  poles 
of  a  Voltaic  battery,  and  the  battery  itself,  during  the  passage  of  elec- 
tricity, exerts  a  certain  action  upon  the  magnetic  needle — and  that  the 
force  which  is  thus  exerted  by  the  conjunctive  wire,  is  at  right  angles 
to  its  axis. 

The  conjunctive  wire  is  also  capable  of  attracting  and  repelling 
the  poles  of  a  magnet.  If,  when  the  magnet  and  connecting  wire  are 
at  right  angles  to  each  other,  the  latter  passing  across  the  centre  of 
the  former,  the  wire  be  moved  along  the  needle  towards  either  ex- 
tremity, attraction  will  take  place  between  the  wire  and  the  adjacent 
pole  ;  and  this  will  occur,  though  the  same  point  of  the  wire  should  be 
presented  in  succession  to  both  of  the  poles.  Again  if  the  position  of 
the  poles  of  the  needle  be  reversed,  they  will  be  repelled  by  the  same 
point  of  the  wire  which  had  previously  attracted  them. — See  Fara- 
day" s  Historical  ^Sketch  of  Electro- Magnetism,  in  Ami.  of  Phil,  xviii. 
198. 

Any  wire,  through  which  a  current  of  electricity  is  passing,  has  a 
tendency  to  revolve  round  a  magnetic  pole,  in  a  plain  perpendicular  to 
the  current ;  and  that,  without  any  reference  to  the  axis  of  the  mag- 
net, the  pole  of  which  is  used.  A  magnetic  pole  also  has  a  tendency 
to  revolve  round  such  a  wire. 

Suppose  the  wire  perpendicular,  its  upper  end  positive,  or  attached 
to  the  positive  pole  of  a  Voltaic  battery,  and  its  lower  end  negative ; 
and  let  the  centre  of  a  watch-dial  represent  the  negative  pole  ;  if  it 
be  a  north  pole,  the  wire  will  rotate  round  in  the  direction  that  the 
watch  hands  move ;  if  it  be  a  south  pole,  the  motion  will  be  in  the 
opposite  direction.  From  these  two,  the  motions  which  would  take 
place  if  the  wire  were  inverted,  or  the  pole  changed  or  made  to  move, 
may  be  readily  ascertained,  since  the  relation  now  pointed  out  remains 
constant. 

These  motions  are  exhibited  in  an  apparatus  devised  by  Mr.  Fara- 
day, or  perhaps  still  better  by  the  revolving  cylinders  of  Ampere. 
They  consist  of  a  cylinder  of  copper,  about  two  inches  high,  and  one 
and  three  fourths  internal  diameter,  within  which  is  a  smaller  cylin- 
der about  one  inch  diameter,  also  of  copper.  The  two  cylinders 
are  fixed  together  by  a  bottom,  having  a  hole  in  the  centre  the  size  of 
the  smaller  cylinder,  leaving  a  circular  cell,  which  may  be  filled  with 
dilute  acid.  A  piece  of  strong  copper  wire  is  fastened  across  the  top 
of  the  inner  cylinder,  and  from  the  middle  of  it  rises  at  right  angles  a 
piece  of  copper  wire,  supporting  a  very  small  metal  cup,  containing  a 
few  globules  of  mercury.  A  cylinder  of  zinc  open  at  each  end,  and 
about  one  and  a  quarter  inch  in  diameter,  completes  the  Voltaic 
combination.  To  the  latter  cylinder  a  wire,  bent  like  an  inverted  U, 
is  soldered  at  opposite  sides,  and  in  the  bend  of  this  wire  a  metallic 
point  is  fixed,  which,  when  fixed  in  a  little  cup  of  mercury,  suspends 
the  zinc  cylinder  in  the  cell,  and  allows  it  a  free  circular  motion. 

On  the  suggestion  of  Mr.  Barlow,  Mr.  Newton  has  fixed  an  ad- 
ditional point,  directed  downwards  from  the  stronger  wire,  which  point 
is  adapted  to  a  small  hole  at  the  top  of  a  bar  magnet.  When  the  ap- 
paratus, with  one  point  only,  is  charged  with  diluted  acid,  and  set  on 


ELECTRO-MAGNETISM.  89 

the  end  of  a  magnet  placed  vertically,  the  zinc  cylinder  revolves  in  a 
direction  determined  by  the  magnetic  pole  which  is  uppermost.  With 
two  points,  the  copper  revolves  in  one  direction,  and  the  zinc  in  a  con- 
trary one.  The  magnet  employed  should  be  a  powerful  one. — Henry, 
i.  215. 

II.  Action  of  the  conjunctive,  wire  vpon  soft  iron  and  steel. — It  was 
about  the  same  time  ascertained,  both  by  Sir  H.  Davy  and  M.  Ara- 
go,  that  magnetism  may  be  developed  in  steel,  not  previously  pos- 
sessing it,  by  being  placed  in  the  electric  current,  and  may  even  be 
excited  by  the  connecting  wire  itself.  Both  philosophers  ascertained, 
independently  of  each  other,  that  the  conjunctive  wire  attracts  iron 
filings,  and  collects  sufficient  to  acquire  the  diameter  of  a  common 
quill.  As  soon  as  the  connection  is  bioken,  the  filings  drop  off,  and 
the  attraction  diminishes  with  the  decaying  energies  of  the  battery. 

In  Sir  H.  Davy's  experiments,  similar  effects  were  produced  by 
common  electricity.  With  a  Leyden  battery  of  seventeen  square  feet, 
discharged  through  a  silver  wire  one-twentieth  of  an  inch  diameter, 
he  rendered  bars  of  steel  two  inches  long  and  from  one-tenth  to  one- 
twentieth  thick,  so  magnetic  as  to  lift  up  pieces  of  steel  wire  and  nee- 
dles ;  and  the  effect  was  communicated  to  needles  at  the  distance  of 
five  inches  from  the  wire,  even  with  the  intervention  of  water  or  thick 
plates  of  glass  or  metal. — Phil.  Trans.  1821,  or  Ann.  of  Pkil.  xviii.  81, 
xix.  1. 

The  theory  of  Ampere,  that  magnets  are  only  masses  of  matter, 
around  the  axis  of  which  electrical  currents  are  moving  in  closed 
curves,  led  M.  Arago  to  expect  a  much  greater  effect,  if  the  connecting 
wires  were  placed  in  the  form  of  a  spiral,  and  the  piece  to  be  magnet- 
ized were  placed  in  its  axis.  This  idea  was  amply  verified  by  experi- 
ment. Having  made  some  of  these  helices,  one  was  connected  by  its 
extremities  with  the  poles  of  a  Voltaic  battery,  and  then  a  needle  wrap- 
ped in  paper,  placed  within  it ;  after  remaining  there  a  few  minutes, 
it  was  taken  out  and  found  to  be  strongly  magnetized  ;  and  the  effect 
of  a  helix  above  that  of  a  straight  connecting  wire,  was  found  to  be 
very  great.  If  the  wire  after  being  formed  into  a  helix,  be  bent  back, 
so  as  to  return  in  a  straight  course  in  the  interior  of  the  cylinder,  with 
the  usual  precautions  against  contact,  we  obtain  a  very  perfect  ac- 
cordance with  the  condition  of  a  magnetic  cylinder  ;  and  to  such  ar- 
rangements the  term  Voltaic  Magnets  may  be  applied  as  being  prefera- 
ble to  that  of  Electro-Dynumic  Cylinders,  given  to  them  by  Ampere. 

This  application  of  the  theory  of  Ampere,  has  led  to  the  most  inte- 
resting and  remarkable  results — having  made  us  acquainted  with  a  me- 
thod of  magnetizing  soft  iron  to  an  extent  heretofore  unknown. 

It  was  found  that  when  the  conjunctive  wire  was  wound  around  a 
bar  of  iron,  bent  in  the  form  of  a  horse-shoe,  while  the  battery  was  in 
action,  the  iron  became  quite  powerfully  magnetic  ;  but  to  produce 
these  effects,  it  was  supposed  that  powerful  Voltaic  instruments  were 
required.  The  first  simplification  of  apparatus  for  this  purpose,  was 
proposed  by  Mr.  Sturgeon,  of  Woolwich,  [Ann.  of  Pkil.  xxviii.  357,]^ 
who  was  enabled  by  his  apparatus  to  render  a  horse-shoe  capable  of 
supporting  nine  pounds,  when  the  opposite  ends  of  the  wires  were 
united  with  the  poles  of  his  Voltaic  arrangement. 

Dr.  Moll,  of  Utrecht,  in  repeating  these  experiments,  used  a  large 
Voltaic  surface.  He  first  employed  a  soft  iron  wire,  bent  in  the  form 
of  a  horse-shoe  ;  the  length  of  the  horse-shoe  being  about  eight  and  a 
half  inches,  and  one  inch  in  diameter.  A  copper  wire  about  one- 


90  ELECTRO-MAGNETISM. 

eighth  of  an  inch  in  diameter  was  twisted  or  coiled  eighty-three  times 
round  the  iron,  from  right  to  left.  The  two  ends  of  the  wire  were 
connected  with  the  opposite  poles  of  a  galvanic  apparatus,  consisting 
of  one  single  copper  trough,  in  which  a  zinc  plate,  having  a  surface  of 
about  eleven  square  feet,  was  immersed.  When  the  Voltaic  appara- 
tus was  rendered  active,  the  horse-shoe  was  capable  of  supporting  fif- 
ty pounds.  A  larger  horse-shoe,  about  twelve  inches  and  a  half  high, 
and  two  and  a  quarter  inches  in  diameter,  and  weighing  about  twen- 
ty-six pounds,  coated  with  silk  and  wound  round,  at  first,  with  forty- 
four  turns  of  brass  wire,  the  acting  Voltaic  surface  being  the  same  as 
before,  supported  135  pounds  ;  with  forty  turns  of  iron  wire  it  support- 
ed 154  pounds. — Brewster's  Edin.  Jour.  N.  S.  iii.  209,  and  Sillimans 
Jour.  xix.  329. 

The  most  recent,  and  by  far  the  most  interesting  experiments  of  this 
kind,  are  those  of  Professors  Henry  and  Ten  Eyck ;  the  object  of 
which  was  not  merely  to  impart  to  soft  iron  its  greatest  magnetic  ef- 
fect, but  with  a  very  small  galvanic  surface.  Around  an  iron  horse- 
shoe, about  nine  and  a  half  inches  high  and  two  inches  square,  and 
weighing  21  pounds,  540  feet  of  copper  bell-wire,  previously  covered 
with  silk  or  cotton  thread,  were  wound  in  nine  coils  of  60  feet  each. 
These  coils  were  not  continued  around  the  whole  length  of  the  bar,  but 
each  strand  of  wire  occupied  two  inches,  and  was  coiled  several  times 
backwards  and  forwards  over  itself;  the  several  ends  of  the  wires  were 
left  projecting,  and  all  numbered,  so  that  the  first  and  last  end  of  each 
strand  might  be  easily  distinguished.  In  this  manner  one  combination 
of  wire  or  more,  could  be  made  by  merely  uniting  the  different  pro- 
jecting ends. 

With  a  single  battery,  consisting  of  two  concentric  copper  cylin- 
ders, with  zinc  between  them,  having  a  surface  of  2-5ths  of  a  square 
foot,  and  which  needed  one  half  pint  of  dilute  acid  for  its  submersion, 
the  horse-shoe  supported,  when  the  extreme  and  opposite  ends  of  all 
the  wires  were  soldered  to  the  zinc  and  copper,  650  pounds.  But 
when  a  zinc  plate  of  twelve  inches  long  and  six  wide,  and  surrounded 
by  copper,  was  employed,  the  horse-shoe  supported  750  pounds. — Sil- 
limaris  Jour.  xix.  400. 

Still  more  recently  these  gentlemen  have  constructed  a  magnet,  con- 
sisting of  a  soft  iron  horse-shoe,  weighing  fifty-nine  and  a  half  pounds, 
and  coiled  with  seven  hundred  and  twenty-eight  feet  of  copper  bell- 
wire,  in  twenty-six  strands,  which  with  a  zinc  surface  of  four  seven- 
ninth  square  feet,  surrounded  by  copper,  supports,  when  the  battery  is 
in  action,  2,063  pounds. — Sillimaris  Jour.  xx.  201. 

III.  Action  of  two  conjunctive  wires  upon  each  other. — It  was  ob- 
served by  Ampere,  that  when  two  conducting  wires  were  so  ar- 
ranged as  that  one  or  both  of  them  were  allowed  a  certain  free- 
dom of  motion,  they  either  attracted  or  repelled  each  other,  accord- 
ing as  the  electric  current  which  was  transmitted  was  moving  in  the 
same  or  in  opposite  directions  in  the  two  wires.  If,  for  example,  two 
wires,  which  are  transmitting  currents  of  electricity,  be  situated  with- 
in a  certain  distance,  and  parallel  to  each  other,  and  if  we  suppose 
the  current  of  positive  electricity  to  be  passing  from  left  to  right,  in 
both  the  wires,  they  will  manifest  an  attraction  for  each  other.  The 
same  tendency  of  attraction  will  also  appear  when  the  positive  cur- 
rents are  both  moving  in  the  contrary  direction,  that  is  from  right  to 
left.  But  if  the  current  in  one  wire  be  moving  in  a  direction  opposite 
to  that  of  the  current  in  the  other  wire,  in  that  case  a  repulsive  action 
will  take  place  between  the  two  wires.  These  were  found  to  be  con- 


ELECTRO-MAGNETISM.  91 

stant  and  invariable  effects  of  the  transmission  of  electricity  along 
conductors  ;  and  they  were  manifested  equally,  whether  the  two  cur- 
rents were  obtained  from  separate  Voltaic  batteries,  or  were  only  two 
portions  of  the  same  current  indifferent  parts  of  its  course. — Quarterly 
Review,  xxxv. 

The  contrast  between  these  attractions  and  repulsions,  and  those 
usually  called  electrical,  is  very  striking.  These  take  place  only  when 
the  circuit  is  completed  ;  those  only  when  it  is  incomplete.  The  at- 
tractions take  place  between  the  similar  ends  of  the  wires,  and  the 
repulsions  between  the  dissimilar  ends  ;  but  the  electrical  attractions 
take  place  between  dissimilar  ends  ;  and  the  repulsions  between  sim- 
ilar ends.  These  take  place  in  vacua,  but  those  do  not.  When  the 
magnetic  attraction  brings  the  two  wires  together,  they  remain  in  con- 
tact ;  but  when  electrical  attraction  brings  two  bodies  together,  they 
separate  after  the  contact. 

It  is  evident,  therefore,  that  these  effects  cannot  be  ascribed  to  elec- 
trical action  ;  it  has  therefore  been  regarded  as  a  magnetic  effect,  and 
an  attempt  has  been  made  to  account  for  it  upon  the  principle  of  the 
vertiginous  action  of  magnetism  arqund  the  axis  of  the  conjunctive  wire. 
But  this,  as  we  shall  presently  see,  is  assumed  by  Ampere,  as  an  ulti- 
mate fact. 

IV.  Action  of  electro-  and  steel  magnets  upon  the  conjunctive  wire,  or 
Volta-  and  Magneto -electric  Induction. 

For  most  of  the  facts  upon  this  new  and  interesting  branch  of  Elec- 
tro-Dynamics we  are  indebted  to  Mr.  Faraday.  It  has  been  shown 
that  when  an  excited  electric  is  brought  near  to  an  insulated  body, 
electricity  is  induced  in  the  body.  After  a  series  of  experiments,  the 
distinguished  philosopher  just  named,  succeeded  in  proving  that  elec- 
tro-magnetic phenomena  could  also  be  exhibited  by  induction.  A  cop- 
per wire  203  feet  in  length  was  passed  in  the  form  of  a  helix  round  a 
large  block  of  wood,  and  an  equal  length  of  similar  wire  was  wound 
on  the  same  block  and  in  the  same  direction,  so  that  the  coils  of 
each  helix  should  be  interposed,  but  without  contact,  between  the  coils 
of  the  other.  The  ends  of  one  of  the  helices  were  connected  with  a 
galvanometer,  and  the  other  with  a  strong  Voltaic  battery,  with  the 
view  of  ascertaining  whether  the  passage  of  a  Voltaic  current  through 
one  helix  would  induce  a  current  in  the  adjoining  helix.  It  was  found 
that  the  galvanometer  needle  indicated  a  current  at  the  moment  both 
of  completing  and  breaking  the  circuit,  but  that  in  the  interval  no  de- 
flexion took  place  ;  and  similarly  the  induced  current  readily  magnet- 
ized a  sewing  needle,  while  the  Voltaic  current  along  the  inducing 
helix  was  in  the  act  of  beginning  and  ceasing  to  flow,  but  at  no 
other  period.  By  varying  the  experiment  the  same  result  was  ob- 
tained :  an  electric  current  transmitted  from  a  Voltaic  battery  through 
a  conducting  helix  does  not  induce  a  current  in  an  adjoining  helix,  ex- 
cept at  the  moment  of  making  or  breaking  the  Voltaic  circuit.  In  the 
former  case  the  direction  of  the  induced  current  is  opposite  to  that  of 
the  inducing  current,  and  in  the  latter  case  it  is  the  same.  This  phe- 
nomenon is  distinguished  by  Mr.  Faraday  under  the  name  of  Volta- 
electric  Induction. 

In  continuing  these  researches,  it  was  also  found  that  the  inducing 
power  of  a  magnet  greatly  exceeds  that  of  an  electric  current.  There 
are  various  arrangements  of  apparatus  for  the  purpose  of  illustrating 
this  fact.  Perhaps  one  of  the  most  convenient  consists  of  a  hollow 
cylinder  of  pasteboard;  round  which  two  compound  helices  were  ad- 


92  ELECTRO-MAGNETISM. 

justed.  On  transmitting  an  electric  current  through  one  helix,  the 
other  deflected  the  galvanometer  and  magnetized  a  needle,  as  in  the 
experiment  jusrdescribed  ;  but  when  a  cylinder  of  soft  iron  was  intro- 
duced into  the  pasteboard  case,  and  a  Voltaic  current  transmitted  as 
before,  the  effect  on  the  galvanometer  was  much  greater.  The  action 
in  this  last  experiment  is  distinguished  by  the  name  of  Magneto -electric 
Induction. 

Upon  carefully  reviewing  these  experiments  and  comparing  them 
with  those  already  described,  in  the  remarks  concerning  the  condition 
of  the  conjunctive  wire  and  its  action  upon  soft  iron,  it  is  evident  that 
the  induced  wire  is  in  the  same  electric  state  as  that  which  unites  the 
two  poles  of  the  battery.  Thus  it  magnetizes  steel,  it  deflects  the  mag- 
net ;  and  by  connecting  a  frog's  leg  with  the  induced  wire  it  is  thrown 
into  spasms,  and  by  arming  the  ends  of  that  wire  with  points  of  char- 
coal and  separating  them  at  the  instant  the  Voltaic  circuit  is  broken  or 
restored,  sparks  of  electricity  are  obtained.  A  Voltaic  current  circulat- 
ing around  a  bar  of  soft  iron  converts  it,  as  we  have  seen,  into  a  tem- 
porary magnet,  and  it  is  to  this  magnet  that  most  of  the  induced  elec- 
tricity is  to  be  ascribed.  Mr.  Faraday  rendered  this  certain  by  sur- 
rounding a  cylinder  of  soft  iron  with  one  helix  connected  with  the  gal- 
vanometer, and  converting  the  soft  iron  into  a  temporary  magnet,  not 
by  a  Voltaic  battery,  but  by  placing  at  each  end  of  the  cylinder  the 
opposite  pole  of  a  magnet.  During  the  act  of  applying  the  magnetic 
poles  to  the  iron,  the  galvanometer  needle  was  deflected  ;  and  the  de- 
llection  was  reproduced,  but  in  an  opposite  direction,  when  the  mag- 
netism of  the  iron  was  ceasing  by  the  removal  of  the  magnet.  So  al- 
so when  a  helix  was  wound  on  a  hollow  cylinder  of  pasteboard,  and  a 
real  magnet  was  introduced,  the  galvanometer  was  deflected  :  the  nee- 
dle then  remained  quiescent  so  long  as  the  magnet  was  left  in  the  cyl- 
inder ;  but  in  the  act  of  its  removal,  the  needle  was  again  deflected, 
though  as  usual  in  the  opposite  direction. 

Thus  it  appears  that  while  magnetism  maybe  induced  by  an  electric 
current,  electricity  may  also  be  induced  in  a  wire  by  a  magnet.  In 
consequence  of  the  intimate  relations  which  are  thus  established  be- 
tween galvanic  and  magnetic  action,  it  was  supposed  that  the  electric 
spark  could  be  obtained  from  the  magnet  itself.  Several  arrangements 
of  apparatus  are  now  constructed,  which  at  first  sight  seem  to  con- 
firm this  conjecture.  But  the  electrical  phenomena  which  they  exhi- 
bit, may  all  be  referred  to  the  principle  of  induction  which  has  just 
been  explained.  By  surrounding  the  middle  of  the  keeper  or  armature 
of  a  common  steel  magnet  with  a  helix  ot  copper  wire  wound  with 
silk,  and  connecting  one  of  the  ends  of  the  wire  with  a  cup  of  mer- 
cury and  removing  the  other  at  the  moment  the  armature  of  soft  iron 
is  withdrawn  from  the  magnet,  a  spark  is  visible  ;  as  also  when  the 
armature  is  applied  and  the  contact  of  the  conducting  wire  restored. 
Of  the  different  forms  of  apparatus  constructed  for  the  purpose  of 
showing  these  effects,  one  of  the  most  convenient  is  that  of  Mr.  Saxton, 
described  in  the  Journal  of  the  Franklin  Institute  for  1834.  In  this 
apparatus  the  keeper  is  made  to  revolve  upon  the  ends  of  the  magnet 
and  around  its  axis ;  and  by  a  peculiar  arrangement  of  the  coils  of 
copper  wire  which  surround  it,  water  may  be  rapidly  decomposed,  and 
shocks  communicated  to  the  mouth  and  tongue.  Dr.  Emmet,  with  an 
other  arrangement,  has  succeeded  in  giving  shocks  so  powerful  that 
they  can  scarcely  be  taken  through  the  arms  and  shoulders  without 
great  inconvenience.  [Sittiman's  Jour,  xxvi,  313.]  And  Dr.  Ritchie 
has  described  a  neat  apparatus  for  firing  an  explosive  mixture  of  oxy- 


ELECTRO-MAGNETISM.  93 

gen  and  hydrogen  gases.  But  I  must  omit  further  details  and  refer 
those  who  wish  to  examine  these  and  other  allied  topics,  to  the  papers 
of  Mr.  Faraday,  Dr  Ritchie,  Mr.  Forbes,  and  others,  most  of  which 
are  published  in  the  recent  volumes  of  the  London  Phil.  Mag.  and  in 
Silliman's  Journal.  The  fourth  English  edition  of  Dr.  Turner's 
Chemistry  also  contains  a  well  digested  summary  of  the  recent  dis- 
coveries in  Electro-Magnetism,  to  which  I  acknowledge  myself  large- 
ly indebted  in  the  preceding  sketch. 

V.  Action  of  the  earth's  magnetism  upon  electric  currents. — Led  by 
his  elaborate  views  of  this  subject,  Ampere  was  induced  to  sub- 
stitute terrestrial  magnetism  for  the  magnet  he  had  previously  used 
in  experiments  on  the  wire.  His  conclusions  were  verified  upon  find- 
ing that  a  conducting  wire,  bent  into  the  form  of  a  circle,  when  free 
to  move,  always  assumes,  by  the  electro- magnetic  action  of  the  earth, 
a  position  in  a  plane  which  is  perpendicular  to  the  magnetic  meri- 
dian. 

This  fact  can  be  shown  in  a  striking  manner,  by  a  small  instrument 
called  De  la  Rive's  Ring.  It  consists  of  a  small  Voltaic  combination, 
or  battery,  attached  to  a  piece  of  cork  ;  the  zinc  plate  is  half  an  inch 
wide  and  three  inches  long,  and  passes  through  the  middle  of  the 
cork,  two  and  a  half  inches  below  and  half  an  inch  above  it ;  the  slip 
of  copper  is  the  same  width  as  the  zinc,  but  about  twice  as  long  ;  it 
passes  through  the  cork  on  both  sides  of  it,  and  being  thus  opposed 
to  both  surfaces,  it  forms  a  little  battery,  on  the  principle  of  Dr.  Wol- 
laston's.  A  piece  of  copper  wire,  covered,  with  silk  thread,  is  rolled 
five  or  six  times  and  tied  together  so  as  to  form  a  ring,  about  an  inch 
and  a  half  in  diameter  ;  the  ends  of  the  wire  are  connected,  one  with 
the  zinc,  and  the  other  with  the  copper  slip  or  plate,  above  the  cork. 
Now  when  this  little  battery  is  placed  in  water,  slightly  acidulated 
with  sulphuric  or  nitric  acid,  the  ring  becomes  magnetic,  and  on  pre- 
senting a  magnetic  bar  to  it,  which  is  strongly  charged,  it  will  be 
attracted  and  repelled,  according  as  one  or  the  other  of  the  poles 
is  opposed,  or  as  one  or  the  other  side  of  the  ring  is  presented  to  the 
bar. 

If  instead  of  connecting  the  copper  and  zinc  by  a  ring,  it  is  done  by 
a  helix  of  copper,  and  the  instrument  then  floated  on  dilute  acid,  the 
helix  becomes  magnetic  ;  -  its  extremities  act  like  the  opposite  poles 
of  a  magnetic  needle,  being  attracted  or  repelled  by  the  opposite  ends 
of  a  magnetic  bar,  and  it  settles  in  a  north  and  south  position,  in  the 
same  manner  as  a  common  magnetic  needle. 

THEORY    OF    ELECTRO-MAGNETISM. 

Different  theoretical  views  of  the  phenomena  of  Electro-Magnet- 
ism have  been  offered.  But  those  of  M.  Ampere  are  the  most  ex- 
tensive and  precise,  and  have  been  tested  by  the  application  of  facts 
and  calculations  very  far  beyond  any  of  the  rest.  They  have  also 
been  found  a  safe  guide  in  experiment,  and  many  of  the  most  inter- 
esting facts  of  the  science  are  direct  consequences  from  them.  Of 
these  views  the  following  is  a  very  brief  outline  ;  but  as  the  theory  of 
two  electrical  fluids  is  adopted  by  Ampere,  they  are  here  made  to  con- 
form with  that  of  one  fluid  employed  throughout  this  work. 

When  a  wire  of  any  metal  connects  the  opposite  poles  of  a  Voltaic 
battery  in  action,  it  is  supposed  that  a  current  of  electricity  is  circu- 
lating from  the  positive  to  the  negatilte  side  of  the  battery,  and  it  is 


94 


ELECTRO-MAGNETISM. 


only  when  electricity  is  thus  moving,  that  magnetic  phenomena  are 
produced. 

While  others  attempt  to  explain  the  attraction  which  is  observed 
between  currents  when  they  move  parallel  to  each  other  in  a  similar 
direction,  and  the  repulsion  between  currents  moving  parallel  to  each 
other  in  opposite  directions,  Ampere  assumes  these  as  the  fundamental 
or  ultimate  facts. 

Ampere  supposes  that  all  magnetic  bodies,  and  the  globe  of  the  earth 
among  the  number,  derive  their  magnetic  properties  from  currents  of 
electricity  continually  circulating  among  the  parts  of  which  they  are 
composed,  and  having,  with  respect  to  the  axes  of  these  bodies,  one 
uniform  direction  of  revolution. 

In  order  to  render  these  views  more  precise,  let  us  conceive  a  slender 
cylinder  of  iron,  intersected  by  an  infinite  number  of  planes,  perpen- 
dicular to  the  axis,  so  as  to  divide  it  into  as  many  circular  disks,  suc- 
cessively applied  to  each  other,  as  represented  in  the  annexed  diagram  : 
let  us  now  imagine  that,  in  consequence  of  some  unknown 
action  among  the  particles  composing  these  circles,  a  cur- 
rent of  electricity  is  perpetually  circulating  in  their  cir- 
cumferences, as  if  they  had  composed  a  Voltaic  circuit. 
Let  us  suppose  the  direction  of  these  currents  to  be  the 
same  throughout  the  whole  series  of  circles  :  the  cylinder 
thus  constituted  may  be  considered  as  a  magnetic  fila- 
ment ;  that  extremity  in  which,  when  uppermost,  the  cur- 
rent of  positive  electricity  is  moving  in  a  direction  con- 
trary to  the  hands  of  a  watch,  being  the  one  which  has 
the  northern  polarity,  that  is  to  say,  which,  when  sus- 
pended as  in  a  compass  needle,  points  to  the  north. 

Setting  out  then,  with  the  assumptions  that  parallel  cur- 
rents attract  one  another  when  their  directions  are  the 
same,  and  repel  one  another  when  opposite  ;  and  that  a  magnet  con- 
sists of  an  infinite  number  of  circular  currents  of  electricity,  all  the 
facts  of  the  science,  now  known,  can  be  easily  explained. 

We  have  seen  that  when  the  conjunctive  wire  is  brought  near  to  a 
magnetic  needle,  it  is  deflected  to  the  east  or  west  according  as  the 
wire  is  brought  above  or  below  the  needle.  In  order  to  understand 
this  fact,  and  the  course  of  the  deflection,  we  have  only  to  suppose 
electric  currents  passing  round  the  needle  from  west  to  east  as  repre- 
sented. Now  when  the  conjunctive  wire  is  brought  over,  and  in  a 
direction  parallel  to  the  magnetic  north  and  south,  the  current  of 
positive  electricity  passing  from  north  to  south,  the  north  end  of  the 
needle  will  be  deflected  to  the  east,  because  the  current  in  the  wire  and 
those  in  the  magnet  will  then  move  in  similar  directions.  For  the 
same  reason  also,  when  the  wire  thus  arranged,  is  brought  under  the 
needle,  it  will  be  deflected  to  the  west,  because  then  also  the  currents 
will  be  in  similar  directions.  When  the  position  of  the  conjunctive  wire 
is  reversed,  that  is,  when  the  supposed  electric  current  passes  from 
south  to  north,  it  will,  when  brought  over  the  needle,  cause  it  to  de- 
viate to  the  west ;  when  brought  under  it,  to  the  east.  All  these  re- 
sults precisely  accord  with  experiments,  and  they  are  also  supported 
by  the  most  exact  mathematical  calculations. 

The  revolutions  of  the  wire  around  magnets  were  regarded  by  most 
philosophers  as  indicative  of  a  rotary  tendency  being  an  ultimate  fact, 
but  they  will  be  found  upon  an  attentive  examination  to  be  direct  con- 
sequences of  Ampere's  theory^  and  are  indeed,  among  the  strongest 
confirmations  of  its  truth.  So  also  the  phenomena  of  electro-magnetic 


ELECTRO-MAGNETISM.  95 

induction,  and  the  action  of  terrestrial  magnetism  upon  electrical  cur* 
rents,  are  precisely  such  as  might  have  been  deduced  from  it. 

REFERENCES.  Faraday's  Historical  Sketch  of  Electro -Magnetism,  up  to 
1822,  Ann.  of  Phil,  xviii.  195,  274,  xix.  107.  Professor  Oersted  on  Electro- 
Mugnetisiii,  Arm.  of  Phil,  xviii.  321 — contains  his  own  account  of  his  theory, 
and  his  objections  to  that  of  Ampere.  Professor  Green,  of  Philadelphia,  on 
Electro-Magnetism.  (  This  little  work  contains  a  good  account  of  the  prin- 
cipal facts  of  the  science  up  to  1827,  with  descriptio7is  and  plates  of  appara- 
tus, Sfc.)  Art.  Electro-Magnetism  in  the  Quarterly  Review,  xxxv. — contains 
an  exposition  of  the  theory  of  Ampere,  shewing  its  application  to  all  the  facts 
of  the  science.  Professor  Cu  mining's  Manual  of  Electro- Dynamics.  Bar- 
t  iw's  Essay  on  Magnetic  Attractions.  Walking  popular  Sketch  of  Elec- 
tro Mignetism.  The  article  Electro-Magnetism,  in  the  Library  of  Useful 
Knowledge,  by  Dr.  Roget. 

THERMO-ELECTRICITY. 

Thermo-electric  phenomena  are  those  which  result  from  currents  of 
electricity,  which  can  be  excited  in  metals  by  mere  variations  of  tem- 
perature. Seebeck  demonstrated  the  existence  of  these  currents  in 
1821,  and  this  observation  was  one  of  the  first,  as  well  as  the  most  in- 
genious applications,  of  the  discovery  of  Oersted. 

If  a  magnetic  needle  be  placed  upon  a  pivot  within  a  rectangle, 
formed  of  a  bar  of  antimony  or  bismuth,  with  a  slip  of  copper  or  a 
copper  wire  soldered  to  each  of  its  extremities,  and  the  heat  of  a  lamp 
applied  to  one  end  of  the  bar,  the  needle  will  be  deflected  and  tend  to 
place  itself  at  right  angles  to  the  magnetic  meridian.  If  that  end  be 
allowed  to  cool,  the  needle  returns  to  its  former  position,  and  if  now 
the  opposite  end  of  the  bar  be  heated,  the  needle  is  deflected  in  a  direc- 
tion contrary  to  that  in  the  former  case.  Similar  phenomena  will  also 
be  observed  when  either  of  the  ends  are  cooled  down  below  the  natural 
temperature. 

Thermo-electricity  may  also  be  developed  in  a  homogeneous  metallic 
mass,  or  in  two  distinct  masses  of  the  same  metal  unequally  heated  at 
their  point  of  contact.  Nor  is  it  confined  to  the  simple  metals, — char- 
coal, plumbago  and  some  of  the  metallic  sulphurets,  are  capable  of  this 
species  of  excitation. 

The  metals  compose  a  thermo-electric  series,  of  which  bismuth  and 
antimony  are  the  extremes,  and  are  the  most  efficacious  within  certain 
limits. 

Rotatory  motion  may  also  be  produced  by  thermo-electrics,  as  first 
shown  by  Professor  Gumming.  Platinum  and  silver  wires  soldered 
together  in  a  circular  form,  rotate,  when  poised  upon  a  magnet  and 
heated  by  a  lamp. 

The  thermo-electric  current  appears  to  be  incapable  of  passing 
through  fluid  non  metallic  conductors,  of  heating  wire  placed  in  its 
circuit,  or  of  magnetizing  steel  or  forming  a  thermo-electric  magnet ; 
and  it  therefore  seems  to  have  no  assignable  tension. — Cumming's  Re- 
port. 

It  has  been  supposed  that  a  thermo-electric  combination  might  be 
employed  as  a  very  delicate  thermometer  ;  and  an  instrument  has  been 
constructed  by  M.  M.  Nobili  and  Melloni,  which  they  denominate  a 
Thermo-multiplier,  and  which  consists  of  such  a  combination,  susceptible 
of  excitation  from  the  feeblest  conceivable  application  of  heat,  and 


96  ELECTRO- NEGATIVE   BODIES. 

connected  with  a  delicate  galvanometer,  which  gives  a  measure  of  the 
effect  produced,  and  consequently  of  the  heat.  [Ann.  de  Chim.  Oct. 
1831.]  This  apparatus  they  have  applied  to  the  examination  of  the 
different  reflecting,  absorbing  and  radiating  power  of  surfaces.  But 
according  to  Professor  Gumming  the  ratio  between  the  temperatures 
and  the  corresponding  deviations  of  a  needle,  in  the  thermo-electric 
circuit,  is  not  invariable,  the  deviations  increasing  slower  than  the 
temperature,  the  law  of  which  deviation  is  unknown  ;  and  hence  a 
pyrometer  constructed  on  thermo-electric  principles  gives  inaccurate 
indications. 

The  theoretical  views  which  have  been  heretofore  offered*  are  appli- 
cable to  the  phenomena  of  thermo-electricity. 

REFERENCES.  Experiments  on  Thermo- Electricity  by  Fourier  and  Oers- 
ted, Ann.  of  PhiL  xxi.  439.  Professor  Camming* s  Report  on  the  same, 
published  in  the  Reports  of  the  British  Association  for  1832.  Sturgeon'y 
papers  in  the  Phil.  Mag.  and  Ann.  for  1831.  Emmet  upon  Caloric  as  a  cause 
of  Galvanic  Currents.  Sill.  Jour,  xxv.  269.  Most  of  the  general 
referred  to  under  the  last  head,  contain  notices  of  Thermo- Electricity.* 


CHAPTER  VI. 


ELECTRO-NEGATIVE    BODIES. 

Having  now  treated  of  the  general  powers,  &c.  I  come  next  to  the 
chemical  history  of  individual  substances,  and  in  conformity  to  the  re- 
marks which  have  been  made,  when  noticing  the  electro-chemical  the- 
ory of  Davy,  I  shall  adopt  that  as  the  basis  of  their  arrangement,  at 
least  so  far  as  inorganic  chemistry  is  concerned. 

The  first  class  of  bodies  to  be  examined,  are  those  which  being  at- 
tracted by  positively  electrified  bodies,  are  inferred  to  be  themselves 
negative.  They  may  be  termed,  for  the  sake  of  brevity,  Electro-Nega- 
tive Bodies.  Though  highly  important,  from  their  influence  as  chem- 
ical agents,  yet  their  number  is  but  small,  for  they  consist  only  of  OXY- 
GEN, CHLORINE,  BROMINE,  IODINE,  and  a  fifth  body,  which  is  only  very 
imperfectly  known  to  us,  FLUORINE. 

These  bodies  have  also  been  classed  together,  from  another  circum- 
stance of  resemblance,  that  of  being  what  has  been  termed  supporter? 
of  combustion.  But  the  term  combustion,  is  now  used  to  express  all 
chemical  combinations  which  are  accompanied  with  the  extrication  of 
heat  and  light ;  phenomena,  for  the  production  of  which,  the  presence 
of  these  bodies  is  by  no  means  essential. 

Before  proceeding  to  a  notice  of  these  individual  substances,  it  may 
be  proper  to  explain  the  principles  upon  which  the  nomenclature,  now 
generally  adopted  by  chemists,  is  founded. 

When  bodies  unite  with  oxygen,  two  sets  of  compounds  are  pro- 
duced, differing  in  many  respects  from  each  other  :  the  one  called  ox- 
ides or  salifiable  principles ;  the  other  acids  or  salifying  principles.  The 
oxides  differ  from  the  acids  in  the  want  of  the  sour  taste  which  gene- 
rally belongs  to  the  latter,  and  in  their  not  changing  vegetable  blue 
colours  to  red  ;  but  they  are  better  characterized  by  the  fact,  that  they 
combine  with  acids  and  form  bodies  which  are  termed  salts.  In  some 


ELECTRO-NEGATIVE   BODIES.  97 

cases  the  oxides  possess  properties  termed  alkaline  ;  but  there  are  both 
acids  and  alkalies  which  do  not  contain  oxygen. 

Oxygen  may  combine  with  a  body  in  several  proportions,  and  form 
both  oxides  and  acids.  If  there  be  many  oxides  of  the  same  base,  the 
Greek  numerals  are  prefixed  to  express  the  different  proportions  of  oxy- 
gen, as  prot-oxide,  deut-oxide,  trit-oxide,  and  per-oxide  ;  the  latter  al- 
ways expressing  the  highest  degree  of  oxidizement  in  oxides. 

When  two  acids  are  formed  by  the  union  of  different  proportions  of 
oxygen,  that  which  contains  the  smallest  quantity  is  designated  by 
the  termination  ous ;  the  other  by  the  termination  ic.  Thus,  nitrous 
acid  contains  four  proportions  of  oxygen  ;  nitric  acid  five  proportions. 
The  acid  containing  a  still  less  amount  of  oxygen  than  the  nitrous,  is 
called  the  hypo- nitrous.  And  if,  as  is  the  case  with  the  sulphurous 
and  sulphuric  acids,  there  be  an  acid  intermediate,  it  is  called  the  hypo- 
sulphuric. 

The  compounds  of  chlorine  are  called  chlorides ;  of  bromine,  bro- 
mides; of  iodine,  iodides;  and  of  fluorine,  fluorides;  when  they  do 
not  possess  acid  properties.  When  they  form  more  than  one  such 
compound  with  a  body,  or  when  the  compound  is  acid,  the  principles 
already  laid  down  will  apply. 

Many  acids  are  formed  by  the  union  of  hydrogen  with  other  bodies. 
The  name  of  such  acids  has  the  usual  termination,  the  term  hydro  be- 
ing prefixed  ;  as  hydro-chloric,  hydri-odic. 

In  the  compounds  of  non-metallic  combustibles,  or  electro-positive 
bodies  with  metals,  the  termination  met  is  added  ;  thus  sulphur  and 
iron  form  sulphuret  of  iron,  &c. 

When  an  acid  combines  with  any  salifiable  basis,  if  the  resulting 
compound  does  not  effect  either  the  tests  of  acids  or  alkalies,  it  is 
called  a  neutral  salt.  Acids  terminating  in  ous,  when  they  combine 
with  alkalies  or  oxides,  change  that  termination  into  ite ;  and  acids 
terminating  in  ic  change  it  to  ate.  Thus,  sulphite  of  soda  consists  of 
sulphurous  acid  and  soda  ;  sulphate  of  soda,  of  sulphuric  acid  and  soda. 
A  salt,  in  which  two  proportions  of  an  acid  are  combined  with  one  of 
a  basis,  has  the  same  term  bi  prefixed.  Thus  we  have  a  carbonate  and 
a  ^i-carbonate  of  soda. 

When  an  acid  combines  with  a  protoxide  of  a  metal,  the  salt  has  the 
term  proto  prefixed  ;  and  when  with  a  peroxide,  the  term  per  ;  thus  we 
have  a  proto  -sulphate  and  a  per-sulphate  of  iron. 

By  carefully  studying  the  principles  which  have  thus  been  briefly 
laid  down,  the  learner  will  find  his  progress  in  the  knowledge  of  chem- 
ical compounds  much  facilitated.  It  should  be  remarked,  however, 
that  although  very  generally  applicable,  there  are  occasional  instances 
of  deviation  from  these  rules. 

The  bodies  about  to  be  described,  exist  in  one  of  three  forms,  viz. 
solid,  liquid  and  gaseous,  or  ceriform.  The  two  former  of  these  terms 
are  sufficiently  understood.  But  it  may  be  observed,  that  the  term  gas 
is  applied  to  all  permanently  elastic  fluids,  except  the  atmosphere,  to 
which  the  term  air  is  appropriated  :  hence  we  shall  be  easily  enabled 
to  distinguish  between  a  gas  and  a  vapour. 

For  performing  experiments  on  the  gases,  various  articles  of  appa- 
ratus are  required,  as  a  pneumatic  trough,  receivers,  gasometers,  &c.  for 
descriptions  of  which  we  must  refer  to  more  extended  treatises. 

Some  bodies  are  called  simple  or  elementary,  by  which  is  to  be  under- 
stood, not  that  they  are  incapable  of  further  decomposition,  but  only 
that  they  have  not  yet  been  decomposed.  We  are  at  present  acquainted 
with  fifty-four  of  these  elementary  bodies. 


98  OXYGEN. 

Compound  bodies  are  formed  by  the  union  of  two  or  more  simple 
ones,  and  their  nature  is  determined  by  two  kinds  of  proof,  viz.  syn- 
thesis and  analysis.  Synthesis  consists  in  effecting  the  chemical  union 
of  two  or  more  bodies  ;  and  analysis,  in  separating  them  from  each 
other,  and  exhibiting  them  in  a  separate  state. 

SECTION  I. 

OXYGEN. 

'Atom.  Num.  S—Symb.  O—Sjp.  gr.  1-111  air=L* 

SYX.     Dephlogisticated  Air — Priestley.     Empyreal  Air — Scheele. 

Discovered  by  Priestley,  in  1774  ;  but  received  its  present  name  from 
Lavoisier. 

PROPERTIES.  In  the  most  simple  form  in  which  we  can  procure  it, 
it  is  gaseous,  insipid,  colourless,  inodorous,  a  powerful  supporter  of 
respiration  and  combustion  ;  sparingly  absorbed  by  water  ;  when  sud- 
denly compressed,  emits  light  and  heat ;  refracts  light  less  than  any 
other  gas. 

A  supporter  of  respiration  and  animal  life. — This  can  be  shown  by 
confining  a  small  animal,  as  a  mouse,  in  a  vessel  of  oxygen  gas  and 
another  in  a  vessel  of  the  same  size,  filled  with  common  air.  The 
animal  in  the  former,  will  live  thrice  as  long  as  in  the  latter.  Or  if 
we  place  a  glow-worm  within  ajar  of  oxygen  gas,  in  a  dark  room,  the 
insect  will  shine  with  much  greater  brilliancy  than  it  does  in  atmos- 
pheric air,  and  appear  more  alert. 

A  powerful  supporter  of  combustion. — This  can  be  shown  by  several 
interesting  and  brilliant  experiments.  Thus  a  lighted  taper,  when 
introduced  into  a  vessel  of  this  gas,  burns  with  great  brilliancy,  and 
if  the  taper  be  blown  out,  and  let  down  into  a  vessel  of  it  while  the 
snuff  remains  red  hot,  it  instantly  kindles  with  a  slight  explosion. 
Lighted  charcoal  emits  beautiful  scintillations  in  oxygen  [gas,  and 
phosphorus  burns  with  such  splendour  that  the  eye  cannot  bear  its  im- 
pression. Even  iron  wire  or  a  steel  watch  spring,  when  formed  into 
a  coil  and  heated  at  one  end  to  redness,  undergoes  rapid  combustion 
in  it. 

It  is  important  to  notice  that  in  all  the  foregoing  experiments  the 
volume  of  the  oxygen  gas  has  diminished  during  the  combustion. — 
This  is  owing  to  its  combination  with  the  burning  body.  Oxygen  gas 
is  supposed  to  be  a  compound  of  oxygen,  light  and  heat.  During 
combustion  in  it,  the  light  and  heat  are  given  out,  and  there  remains 
a  compound  of  solid  oxygen  with  the  combustible.  Thus  when  iron 
wire  is  burned  in  oxygen  gas,  light  and  heat  are  evolved,  and  there 
remains  a  substance,  which,  upon  examination,  proves  to  be  an  oxide 
of  iron,  composed  of  oxygen  andiron,  and  the  increase  of  weight  in  the 
iron  is  exactly  equal  to  the  diminution  of  weight  in  the  oxygen  gas. 
The  same  thing  occurs  during  the  combustion  of  phosphorus,  sulphur, 
carbon,  &c.  in  this  gas,  though  in  these  cases  acids,  instead  of  oxides, 
are  formed. 


*  I  have  endeavoured  lo  consult  the  convenience  of  the  student  by  placing 
under  the  name  of  each  substance  its  equivalent  or  atomic  number,  the  symbol 
by  which  it  is  expressed,  and  its  specific  gravity. 


OXYGEN.  99 

Respiration  has  the  same  effect  upon  oxygen  as  combustion.  If  an 
animal  be  confined  in  a  limited  quantity  of  atmospheric  air,  it  will  at 
first  feel  no  inconvenience ;  but  as  a  portion  of  oxygen  is  withdrawn 
at  each  inspiration,  its  quantity  diminishes  rapidly,  so  that  respiration 
soon  becomes  laborious,  and  in  a  short  time  ceases  altogether.  Ano- 
ther animal  introduced  into  the  same  air,  expires  in  the  course  of  a 
few  seconds,  and  if  a  lighted  candle  be  immersed  in  it,  the  flame  will 
be  extinguished. 

NATURAL  STATE.  Oxygen  gas  can  scarcely  be  said  to  exist  in  a  se- 
parate state  in  nature.  In  some  saltpetre  caves,  perhaps,  there  is  an 
excess  of  it,  over  that  which  commonly  forms  atmospheric  air. 

EXTRACTION.  This  gas  may  be  obtained  by  heating  to  redness  any 
substance  which  contains  a  large  proportion  of  oxygen,  as  the  chlorate 
or  nitrate  of  potassa,  peroxide  of  manganese  and  red  lead.  Chlorate  of 
potassa  furnishes  the  most  pure  gas  ;  but  this  requires  more  cautious 
management.  Peroxide  of  manganese  is  generally  employed.  This 
is  to  be  heated  to  redness  in  a  gun-barrel  or  iron  retort,  to  which  a 
tube  is  attached.  The  gas  is  collected  over  water.  The  first  por- 
tions should  be  rejected  as  containing  atmospheric  air,  and  some- 
times carbonic  acid,  owing  to  the  impurity  of  the  manganese.*  The 
gas  should  always  be  tested  with  a  taper  before  it  is  collected  for  ex- 
periment. 

The  rationale  of  all  these  processes  accords  with  the  views  before 
given,  and  will  be  readily  understood.  Chlorate  of  potassa,  peroxide 
of  manganese  and  red  lead  contain  a  large  proportion  of  oxygen. — 
Upon  the  application  of  heat  the  oxygen  is  rendered  gaseous  and  it 
then  escapes. 

TEST.  M.  Kastner  has  proposed  protoxide  of  iron  as  a  test  for 
the  presence  of  oxygen  in  gaseous  mixtures. — Phil.  Mag.  and  Ann. 
v.  235. 

ACTION  UPON  THE  ANIMAL  ECONOMY.  Although  oxygen  gas  is  essen- 
tial to  the  support  of  animal  life,  it  appears,  when  pure,  to  excite  so 
great  a  degree  of  excitement  in  the  pulmonary  organs  as  to  render  it 
hazardous  to  breathe  it  for  any  length  of  time.  Thenard  relates  a 
case  in  which  it  proved  fatal.  And,  in  an  experimental  enquiry  into 
the  physiological  effect  of  oxygen  gas  upon  the  animal  system,  by  Mr. 
Broughton,  the  author  shows  that  the  symptoms  induced  by  its  respir- 
ation are  analogous  to  those  which  follow  the  absorption  of  certain 
poisons  into  the  system. — Phil.  Mag.  and  Ann.  v.  383.  Brande's  Jour. 
N.  S.  vii.  1. 

REFERENCES.  Scheele  on  air  and  fire.  Priestly  on  Airs.  Lavoisier1  s 
Elements  of  Chemistry.  Thenard  describes  an  apparatus  for  showing  the 
evolution  of  Light  by  the  compression  of  Oxygen  Gas,  Traite  de  Chim,  i. 
181.  A  convenient  apparatus  for  procuring  Oxygen  Gas,  from  Chlorate  of 
Potassa,  is  described  anil  figured  by  Berzelius,  Traite  de  Chim.  i.  207.  On 
the  specific  gravity  of  Oxygen,  see  Thomson's  First  Prin.  where  the  esti- 
mate of  Dr.  Prout,  as  above  given  is  confirmed. 

*  The  carbonate  of  lime  to  which  this  is  due,  may  be  separated  by  washing 
the  manganese  with  dilute  muriatic  acid  until  effervescence  ceases. 


100  CHLORINE. 

SECTION  II. 

CHLORINE. 
Atom.  Num.  35.45— jStymfc.  Cl— Sp.  gr.  2-47  air=L 

SYN.     Dephlogisticated  Marine  Acid — Scheele.     Oxymuriatic  Acid* 
This   substance  was   discovered  by  Scheele,  in   1774.     It   derives 

its  present   name  from   the  Greek  chloros,  green,  in  allusion  to  its 

colour. 

PROPERTIES.  Gaseous,  having  a  yellowish-green  colour,  an  astrin- 
gent taste  and  disagreeable  odour  ;  one  of  the  most  suffocating  of  the 
gases,  exciting  spasms  and  great  irritation  of  the  glottis,  even  when 
considerably  diluted  with  air ;  emits  light  and  heat  when  strongly  and 
suddenly  compressed  ;  under  a  pressure  of  four  atmospheres  becomes 
a  limpid  liquid  of  a  bright  yellow  colour  ;  is  absorbed  by  cold  water, 
from  whence  it  can  again  be  driven  by  heat ;  supports  combustion  ; 
discharges  animal  and  vegetable  colours,  when  water  is  present ;  and 
is  a  powerful  disinfectant. 

Chlorine  is  absorbed  by  cold  water. — Cold  recently  boiled  water,  at 
the  common  pressure,  absorbs  twice  its  volume  of  chlorine.  Hence 
a  solution  of  chlorine  may  be  easily  made  by  transmitting  a  current  of 
the  gas  through  cold  water.  It  has  the  taste,  colour  and  most  of  the 
other  properties  of  the  gas  itself.  When  moist  chlorine  gas  is  exposed 
to  a  cold  of  32°  F.  yellow  cryslals  are  formed,  which  consist  of  water 
and  chlorine  in  definite  proportions.  They  are  composed,  according 
to  Mr.  Faraday,  of  one  atom  of  chlorine,  and  ten  atoms  of  water, 
and  have  received  the  name  of  Hydrate  of  Chlorine. — Phil.  Trans.  1823. 
Ann.  of  Phil,  xxiii.  89. 

Supports  combustion. — Some  substances  unite  with  chlorine  with  the 
evolution  of  light  and  heat,  and  hence  it  is  called  a  supporter  of  com- 
bustion. In  this  respect,  however,  it  differs  considerably  from  oxygen 
gas.  If  a  lighted  taper  be  plunged  into  a  vessel  of  chlorine  gas,  it 
burns  for  a  short  time  with  a  small  red  flame,  and  emits  a  large  quan- 
tity of  smoke.  Phosphorus  takes  fire  in  it  spontaneously,  arid  burns 
with  a  pale  white  light,  if  the  temperature  of  the  gas  be  raised  to 
about  70°  F.  Several  of  the  metals,  such  as  tin,  copper,  arsenic,  anti- 
mony and  zinc,  when  introduced  into  chlorine  in  the  state  of  powder, 
or  of  fine  leaves,  are  suddenly  inflamed.  Great  caution  should  be  ob- 
served in  performing  these  experiments  to  prevent  the  gas  from  being 
inhaled. 

In  all  these  cases  of  combustion  in  chlorine  gas,  the  chlorine  com- 
bines with  the  combustible,  and  there  result  a  class  of  compounds 
named  Chlorides  or  Chlorurets.  These  are  sometimes  acid  and  some- 
times destitute  of  that  property. 

Discharges  colours. — This  assertion  is  correct  when  applied  to  chlo- 
rine as  it  is  usually  obtained.  But  Sir  H.  Davy  proved  that  chlorine, 
when  perfectly  dry,  does  not  bleach.  When  combined  with  water, 
it  possesses  the  property  of  bleaching  in  an  eminent  degree.  This 
may  be  shown  by  introducing  a  solution  of  indigo  or  strips  of  calico 
into  solution  of  chlorine.  In  a  short  time  the  colours  will  be  com- 
pletely discharged,  and  they  can  never  be  restored.  Hence  an  im- 
portant practical  application  of  chlorine,  and  some  of  its  compounds, 
in  the  art  of  bleaching. 


CHLORINE.  101 

Is  a  powerful  disinfecting  agent. — The  power  of  chlorine,  for  the  pur- 
poses of  fumigation,  was  shown  by  Guyton-Mor\eau,  who  ascertain- 
ed that  it  destroyed  the  volatile  principles  given  off  .by  petrifying 
animal  matters.  It  probably  acts  in  a  similar  way*  on  contagious  ef- 
fluvia. It  is  now  extensively  employed  as  a  disinfecting  agent,  either 
in  solution  in  water,  or  in  the  form  of  those,  peculiar  corr>  pounds,  of 
chlorine  and  soda,  and  chlorine  and  lime,  which  have  received  the 
names  of  Labarrague's  disinfecting  liquor,  and  Tennant's  bleaching  pow- 
der, and  which  I  shall  notice  hereafter. 

It  has  been  ascertained  that  the  bleaching  and  disinfecting  powers 
of  chlorine  are  in  exact  proportion  to  each  other,  and  it  is  probable 
that  both  these  effects  are  produced  in  a  similar  way.  During  the 
process  of  bleaching,  water  is  decomposed,  in  consequence  of  the 
great  affinity  between  chlorine  and  hydrogen  ;  the  decomposition  of 
the  colouring  matter  is  occasioned  by  the  oxygen  which  is  liberated  ; 
at  the  same  time  muriatic  acid  is  always  generated.  The  bleaching 
property  of  the  deutoxide  of  hydrogen,  of  which  oxygen  is  certainly 
the  decolourizing  principle,  strengthens  this  view.  The  power  of 
chlorine,  as  a  disinfecting  agent,  depends  also  upon  its  great  affinity 
for  hydrogen,  a  substance  entering  largely  into  putrid  affluvia,  by 
means  of  which  they  are  decomposed.  This  is  illustrated  in  the  cases 
of  sulphuretted  and  carburetted  hydrogen,  which  are  in  this  way  de- 
composed by  chlorine,  and  rendered  innoxious. 

NATIVE  STATE.  Chlorine  exists  in  nature  in  great  abundance,  but 
always  combined  with  other  bodies.  Some  of  these  compounds  are 
very  abundant,  as  muriatic  acid,  which  is  often  thrown  out  in  great 
quantities  by  volcanoes,  and  chloride  of  sodium  which  occurs  in  the 
form  of  rock  salt,  and  also  in  solution  in  the  waters  of  the  sea,  &c. 

PREPARATION.     Chlorine  gas  may  be  obtained, 

1.  By  mixing  concentrated  muriatic  acid,  contained  in  a  glass  flask 
or  retort,  with  half  its  weight  of  peroxide  of  manganese.     Upon  the 
application  of  heat  the  gas  is  freely  evolved.     It  should  be  collected 
over  warm  water,  in  inverted  glass  bottles  filled  with  the  same  liquid, 
and  when  the  water  is  wholly  displaced  by  the  gas,  the  bottles  should 
be  closed  with  stoppers. 

In  this  process  a  part  of  the  muriatic  acid  is  decomposed  ;  its  hy- 
drogen combines  with  one  atom  of  the  oxygen  of  the  manganese,  and 
forms  water,  while  the  chlorine  is  disengaged.  At  the  same  time 
also  protoxide  of  manganese  combines  with  an  undecomposed  portion 
of  muriatic  acid  and  forms  muriate  of  the  protoxide  of  manganese, 
which  remains  in  the  retort. 

2.  The  more  common  and  cheaper  method  of  preparing  chlorine,  is 
to  mix  intimately  three  parts  of  common  salt  and  one  part  of  the  per- 
oxide of  manganese,   and  to  this  mixture  add  two  parts  of  sulphuric 
acid,  diluted  with  an  equal  weight  of  water. 

In  this  case,  sulphuric  acid  acting  upon  the  solution  of  common 
salt,  disengages  muriatic  acid,  which  is  decomposed  by  the  peroxide  of 
manganese  in  the  manner  just  explained.  The  residuum  in  this  case, 
however,  is  the  sulphate  of  manganese  and  sulphate  of  soda. 

TESTS.  Chlorine  may  in  general  be  recognized  by  its  colour  and 
odour.  Chemically,  it  may  be  detected  by  its  bleaching  property, 
and  by  the  circumstance  that  a  solution  of  the  nitrate  of  silver/  oc- 
casions in  it  a  dense  white  precipitate  (chloride  of  silver,)  which  be- 
comes dark  on  exposure  to  light,  is  insoluble  in  acids,  but  completely 
soluble  in  pure  ammonia. 


102  CHLORINE. 

ACTION  ON  THE  ANIMAL  ECONOMY.  Chlorine  in  a  gaseous  state,  des- 
troys those  who- breathe  it,  by  producing  great  irritation  of  the  bron- 
chia ;*  and  ev^n  wL.en  diluted  with  atmospheric  air,  it  causes  cough 
and  inflammation.  Pelletier  is  thus  said  to  have  fallen  a  victim  to  its 
effects* .  [.Beck's  Med.  Juris.  3d  ed.  503.]  The  antidote  in  such  cases 
is.tanmoT'ia.  In  jsohition,  however,  chlorine  is  employed  medicinally  ; 
in  some  cases  with  great  advantage. — See  Urc's  Chem.  Diet. 

REFERENCES.  Scheele's  Essays.  Memoirs  on  the  nature  of  Chlorine,  by 
Davy,  Van  Moris,  Thomson,  Gay  Lussat  and  Berzelius,  Ann.  of  Phil.  iii. 
iv.  v.  and  vi.  A  comparison  of  the  new  and  eld  theories  of  Chlorine,  by  Ber- 
zelius,  Ann.  of  Phil.  v.  7.  [The  author  ivas,  until  recently,  in  favour  of  the 
old  theory.]  Papers  on  the  controversy  concerning  the  nature  of  Chlorine, 
by  Murray,  Urey  Berthollet  and  Davy,  Ann.  of  Phil.  x.  xi.  xii.  xiii.  For  a 
summary  of  (his  coritroversy  up  to  1813,  see  a  note  of  Dr.  T.  Cooper,  in  the 
1st  volume  of  the  Amprican  edition  of  Thomson's  Chem.  155.  He  hoioever 
inclines  to  the  old  theory,  now  universally  abandoned.  Berzelius  on  the  nature 
of  Muriatic  Acid,  Ann.  of  Phil.  ii.  254. 

CHLORINE    AND    OXYGEN. 

These  substances  unite  in  four  different  proportions.  The  leading 
character  of  these  compounds  depends  upon  the  fact,  that  chlorine  and 
oxygen  have  a  very  feeble  affinity  for  each  other.  They  are  therefore 
never  met  with  in  nature  ;  they  can  hence  also  be  easily  decomposed. 
These  compounds  are  as  follows  : 

Cl.         O. 

Protoxide  of  Chlorine,     -     ....     35-45 8.=r43-45. 

Peroxide  of  Chlorine,       ....     35 -45.... 32.3=67-45. 

Chloric  acid,     - 35-45....40.z=75-45. 

Perchloric  acid, 35 -45.... 56.  —91  -45. 

Protoxide  of  Chlorine—Atom.  Num.  4345—  Symb.  O-f-CI— 
Sp.  gr.  2417  air=l. 

Discovered  by  Sir  H.  Davy  in  1811,  and  described  by  him  under  the 
name  of  Euchlorine. 

PROPERTIES.  Gaseous ;  colour  yellowish-green,  similar  to  that 
of  chlorine,  but  more  brilliant  ;  odour  like  that  of  burned  sugar  ; 
bleaches  vegetable  substances,  but  gives  the  blue  colours  a  red  tint 
before  discharging  them ;  is  highly  explosive  ;  dissolves  in  water  to 
eight  or  ten  times  its  volume  ;  may  be  liquified  by  pressure. 

Protoxide  of  Chlorine  is  highly  explosive. — The  heat  of  the  hand,  or 
the  pressure  occasioned  in  transferring  it  from  one  vessel  to  another, 
sometimes  causes  an  explosion.  This  effect  is  also  occasioned  by  phos- 
phorus, which  bursts  into  flame  at  the  moment  of  immersion.  All 

*  The  recent  experiments  of  Mr.  Soubeiran,  have  rendered  the  existence  of 
this  gas  doubtful  ;  and  (he  same  author  supports  the  opinion  of  Berzelius,  that 
the  bleaching  compounds  contain  a  lower  acid  of  chlorine,  Chlorous  acid. 
But  these  views  are  not  yet  sufficiently  settled  to  warrant  the  alterations,  which 
by  their  adoption,  would  become  necessary. — See  Ann.  de  Chim.  xlviii.,  or 
Johnston* s  Report  on  Chemistry, 


CHLORINE.  103 

burning  bodies  by  their  heat,  occasion  an  explosion,  and  then  burn 
vividly  in  the  decomposed  gas.  With  hydrogen,  it  forms  a  mixture 
which  explodes  by  flame,  or  the  electric  spark,  forming  water  and  mu- 
riatic acid.  The  best  proportion  is  fifty  measures  of  the  protoxide  of 
chlorine  to  eighty  of  hydrogen. 

PREPARATION.  This  gas  is  prepared  by  adding  to  two  parts  of 
chlorate  of  potassa,  one  part  of  strong  muriatic  acid  and  one  of  water. 
These  ingredients  should  be  put  into  a  small  retort,  to  which  gentle 
heat  is  to  be  applied.  The  gas  must  be  collected  over  mercury.  Prof. 
Silliman  recommends  placing  the  materials  in  a  small  glass  flask,  fur- 
nished with  a  tube  bent  twice  at  right  angles,  and  passing  to  the  bot- 
tom of  any  clean  dry  phial,  flask  or  tube,  rather  deep  and  with  a  nar- 
row neck.  A  gentle  heat,  applied  beneath  the  flask,  soon  disengages 
the  euchlorine  gas,  which,  by  its  great  weight,  displaces  the  common 
air  from  the  recipient  and  takes  its  place.  By  using  tongs  properly 
curved,  so  as  to  embrace  the  phials  or  tubes  filled  with  the  gas,  the 
operator  may  perform  all  the  necessary  experiments  without  danger  of 
causing  an  explosion  by  the  warmth  of  the  hands. — Sill.  Jour.  vi.  164- 

REFERENCES.  Sir  H.  Davy,  in  Phil.  Trans.  1811.  Faraday,  on  the 
liquefaction  of  Euchlorine,  Phil.  Trans.  1823,  and  Ann.  of  Phil,  xxiii.  95. 

Peroxide  of  Chlorine — Atom.  Num.  6745— 4O-|-C1— Sp. 
gr.  2-3-16  air=l. 

SYN.  Chlorous  Acid.  Berzelius. — Qitadrozide  of  Chlorine.  Thom- 
son. 

Discovered  by  Sir  H.  Davy  in  1815,  and  soon  after  by  Count  Sta- 
dion  of  Vienna. 

PROPERTIES.  Colour  bright  yellowish-green  ;  odour  aromatic,  with- 
out any  smell  of  chlorine  ;  is  rapidly  absorbed  by  water ;  destroys 
most  vegetable  blues  without  previously  reddening  them ;  does  not 
unite  with  alkalies  ;  occasions  the  combustion  and  explosion  of  phos- 
phorus when  introduced  into  it :  explodes  violently  when  heated  to  a 
temperature  of  212°  F.  emitting  a  strong  light,  and  suffering  a  greater 
expansion  than  the  protoxide  of  chlorine  ;  it  can  be  liquified  by  pres- 
sure. 

PREPARATION.  This  substance  is  formed  by  the  action  of  sulphuric 
acid  upon  chlorate  of  potassa.  A  quantity  of  this  salt,  not  exceeding 
50  or  60  grains,  is  reduced  to  powder  and  made  into  a  paste  by  the  ad- 
dition of  strong  sulphuric  acid.  The  mixture  which  acquires  a  deep 
yellow  colour,  is  placed  in  a  glass  retort,  and  heated  by  warm  water, 
the  temperature  of  which  is  kept  under  212°  F.  The  gas  is  to  be  col- 
lected over  mercury. 

The  changes  which  take  place  in  this  process  may  be  thus  explain- 
ed. The  sulphuric  acid  decomposes  some  of  the  chlorate  of  potassa 
and  liberates  chloric  acid.  The  chloric  acid,  at  the  moment  of  sepa- 
ration, resolves  itself  into  peroxide  of  chlorine  and  oxygen  ;  the  last 
of  which,  instead  of  escaping  as  free  oxygen  gas,  goes  over  to  the  acid 
of  some  undecomposed  chlorate  of  potassa  and  converts  it  into  per- 
chloric acid.  The  whole  products  are  bisulphate  and  perchlorate  of 
potassa  and  peroxide  of  chlorine. 

One  of  the  most  striking  properties  of  this  gas,  can  be  exhibited  on 
a  small  scale,  by  adding  to  a  few  grains  of  chlorate  of  potassa  in  a  test 


104  BROMINE. 

glass  five  or  six  drops  of  strong  sulphuric  acid.  The  gas  is  immedi- 
ately disengaged.  If  a  piece  of  cotton  dipped  in  ether,  be  now  brought 
into  contact  with  the  gas,  it  takes  fire  with  a  slight  explosion.  The 
eotton  should  be  attached  to  a  wire,  and  some  care  is  necessary  in  per- 
forming the  experiment. 

REFERENCES.  Sir  H.  Davy,  in  Phil.  Trans.  1815.  Count  Von  Stadi- 
on,in  Gilbert's  Ann.  der  Phys.  lii.  179,  (Feb.  1816. J  Berzelius,  Trait,  de 
Chitn.  ii.  73, — where  will  be  found  his  reasons  for  calling  this  an  acid. 

Chloric  Acid — Atom.  Num.  7545 — Symb.  50-}-Cl. 
First  obtained  in  a  separate  state  by  Gay  Lussac. 

PROPERTIES.  Reddens  vegetable  blues  ;  has  a  sour  taste  and  forms 
neutral  salts,  called  Chlorates,  with  alkaline  and  earthy  bases  ;  distin- 
guished from  chlorine  by  its  not  being  possessed  of  bleaching  proper- 
ties ;  gives  no  precipitate  with  nitrate  of  silver,  and  can  hence  be  dis- 
tinguished from  muriatic  acid  ;  is  readily  known  by  its  forming  a  salt 
with  potassa  which,  when  thrown  on  burning  charcoal,  deflagrates 
like  nitre. 

PREPARATION.  This  acid  may  be  obtained  by  adding  to  the  chlorate 
of  baryta  a  quantity  of  weak  sulphuric  acid,  exactly  sufficient  for  com- 
bining with  the  baryta.  The  insoluble  sulphate  subsides  and  pure 
chloric  acid  remains  in  the  liquid.  This  may  be  concentrated  by  gen- 
tle heat,  till  it  acquires  an  oily  consistence. 

REFERENCES.  Gay  Lussac,  in  a  memoir  on  Iodine,  #c.  Ann.  of  Phil,  vi, 
129. 

Perchloric  Acid— Atom.  Num.  91-45—  Symb.  7O-fCl— &p. 
gr.  1'65  water=l. 

PREPARATION.  The  saline  matter  which  remains  in  the  retort  after 
forming  the  peroxide  of  chlorine,  is  a  mixture  of  perchlorate  and  bi- 
sulphate  of  potassa ;  and  by  washing  with  cold  water,  the  bisulphate 
is  dissolved,  and  the  perchlorate  is  left.  Perchloric  acid  may  be  pre- 
pared from  this  salt  by  mixing  it  in  a  retort  with  half  its  weight  of 
sulphuric  acid,  diluted  with  one  third  of  water,  and  applying  heat  to 
the  mixture.  At  the  temperature  of  about  2^4°  F.  white  vapours 
rise  which  condense  as  a  colourless  liquid  in  the  receiver.  This  is 
a  solution  of  perchloric  acid.  It  has  an  acid  taste,  and  reddens  litmus 
paper  without  discharging  its  colour,  and  uniting  with  alkalies,  forms 
Perchlorates. 

REFERENCES.  Stadion,  in  Gilbert's  Ann.  der  Phys.  lii.  213.  Berzelius, 
Trait  de  Chim.  ii.  65. 

SECTION  II L 

BROMINE. 
Atom.  Num.  78-26—  Symb.  Dr.— Sp.  gr.  2-966  water=l. 

Discovered  by  M.  Balard  of  Montpelier,  in  182(5,  and  described  by 
him  under  the  name  of  Muridc.  This  has  since  been  changed  to 
Bromine,  from  the  Greek  bromos,  in  allusion  to  its  strong  odour. 


BROMINE.  105 

PROPERTIES.  A  liquid  of  a  deep  reddish-brown  colour ;  odour  dis- 
agreeable, somewhat  resembling  that  of  chlorine  ;  taste  powerful ;  at 
common  temperatures  it  emits  red  coloured  vapours,  which  are  very 
similar  in  appearance  to  those  of  nitrous  acid  ;  and  at  116'5°  F.  it  en- 
ters into  ebullition  ;  between  the  temperature  of  zero  and  — 4°  F.  it 
is  congealed,  and  in  that  state  is  brittle,  but  if  combined  with  water 
so  as  to  form  a  hydrate,  it  affords  fine  red  crystals  at  32°  ;  soluble  in 
water,  alcohol  and  ether,  the  latter  being  the  best  solvent  ;  does  not 
redden  litmus  paper,  but  bleaches  it  rapidly  like  chlorine  ;  supports 
combustion  ;  acts  with  energy  upon  animal  textures,  giving  the  skin  a 
yellow  stain,  and  being  highly  destructive  to  life. 

Bromine  is  volatile. — This  can  be  shown  by  introducing  a  few  drops 
of  the  liquid  into  a  matrass  ;  the  beautiful  red  vapour  will  soon  fill  the 
vessel. 

Supports  combustion. — Antimony  and  tin,  take  fire,  and  potassium 
causes  a  violent  detonation,  when  brought  into  contact  with  bromine. 
Its  vapour  extinguishes  a  lighted  taper,  but  before  going  out  it  burns 
for  a  short  time  with  a  flame  surrounded  by  a  greenish  margin  topped 
with  red. — The  compounds  formed  by  the  union  of  combustibles  with 
bromine,  are  called  Bromides  or  Bromurets. 

NATIVE  STATE.  This  substance  exists  in  sea  water,  in  the  form  of 
hydrobromic  acid,  in  combination  probably  with  magnesia.  In  this 
state  it  apparently  forms  an  essential  ingredient  in  ocean  water ;  for 
it  has  been  detected  in  the  waters  of  the  Mediterranean,  Baltic,  North 
Sea,  and  Frith  of  Forth.  It  has  also  been  found  in  the  waters  of  the 
Dead  Sea,  and  in  many  lime  springs  in  Germany  and  in  our  own 
country.  Finally,  it  has  been  detected  in  the  ashes  of  certain  sea 
weeds,  and  of  some  animals,  as  those  of  the  Janthina  violacea. 

PREPARATION.  Bromine  is  obtained  by  transmitting  a  current  of 
chlorine  gas  through  the  bittern  of  sea  water,  and  then  agitating  a 
portion  of  sulphuric  ether  with  the  liquid.  The  ether  dissolves  the 
whole  of  the  bromine,  from  which  it  receives  a  beautiful  hyacinth 
red  tint,  and  on  standing,  rises  to  the  surface.  When  the  ethereal  so- 
lution is  agitated  with  caustic  potassa,  its  colour  entirely  disappears, 
owing  to  the  formation  of  hydrobromate  and  bromate  of  potassa,  and 
the  former  salt  is  obtained  in  cubic  crystals  by  evaporation.  The 
bromine  may  then  be  set  free  by  means  of  chlorine,  and  separated  by 
heat. 

TESTS.  In  most  cases  bromine  is  easily  detected  by  means  of  chlo- 
rine ;  for  this  substance  displaces  bromine  from  its  combination  with 
hydrogen,  metals  and  most  other  bodies.  The  appearance  of  its  va- 
pour, or  the  colour  of  its  solution  in  ether,  will  then  render  its  pres- 
ence obvious.  Bromine  also  renders  a  solution  of  starch  of  an  orange 
colour. 

REFERENCES.  Balard  on  a  peculiar  substance  contained  in  Sea  Water, 
Ann.  de  Chim.  ft  de  Phys.  xxxii.  337,  and  in  Ann.  of  Phil.  xii.  381,  411 — 
contains  also  a  notice  of  its  compounds.  Phil.  Mag.  and  Ann.  vii.  234.  viii, 
225.  For  a  summary  of  what  was  known  concerning  Bromine  and  its  com- 
pounds  up  to  1828,  see  New-York  Med.  and  Phys.  Jour.  vii.  141.  On  the 
presence  of  Bromine  in  American  saline  Waters,  Sillimari's  Jour,  xviii,  142. 


106  IODINE. 


BROMINE    AND    OXYGEN. 

Only  one  compound  of  bromine  and  oxygen  has  been  hitherto  dis- 
covered, which  is  bromic  acid,  similar  in  its  constitution  to  chloric 
acid.  ' 

Bromic  Acid— -A lorn.  Num.  118-26—  Symb.  5O+Br. 

PROPERTIES.  Odour  scarcely  any  ;  taste  very  acid,  though  not  at 
all  corrosive  ;  reddens  litmus  paper  powerfully  at  first,  and  soon  after 
destroys  its  colour ;  is  not  affected  by  nitric  or  sulphuric  acid,  except 
when  the  latter  is  highly  concentrated,  in  which  case  bromine  is  set 
free,  and  effervescence,  probably  owing  to  the  escape  of  oxygen  gas, 
ensues  ;  unites  with  bases  and  forms  a  class  of  bodies  termed  Bro- 
mates,  analogous  to  the  chlorates. 

PREPARATION.  This  acid  may  be  procured  in  a  separate  state  by 
decomposing  a  dilute  solution  of  bromate  of  baryta,  with  sulphuric 
acid,  so  as  to  precipitate  the  whole  of  the  baryta.  The  resulting 
solution  of  bromic  acid  may  be  concentrated  by  slow  evaporation, 
until  it  acquires .  the  consistence  of  syrup  ;  but  on  raising  the  tem- 
perature, in  order  to  expel  all  the  water,  one  part  of  the  acid  is  vola- 
tilized, and  the  other  resolved  into  oxygen  and  bromine.  The  same 
effect  takes  place  when  the  evaporation  is  conducted  in  vacuo,  with 
sulphuric  acid ;  and  hence  all  attempts  to  obtain  anhydrous  bromic 
acid  have  been  unsuccessful. 


BROMINE    AND    CHLORINE. 

We  are  acquainted  with  one  compound  of  these  elements,  probably 
composed  of  one  atom  of  each. 

Chloride   of  Bromine. 

SYN.     Chlorure  Bromique.     Berzelius. 

PROPERTIES.  A  volatile  fluid,  of  a  reddish-yellow  colour,  much  less 
intense  than  that  of  bromine  ;  odour  penetrating  ;  taste  very  disagree- 
able ;  vapour  of  a  deep  yellow,  like  that  of  the  oxides  of  chlorine  ;  so- 
luble in  water,  in  which  state  it  possesses  the  colour,  odour  and  bleach- 
ing properties  of  the  compound. 

PREPARATION.  This  compound  may  be  formed  at  common  tempera- 
tures, by  transmitting  a  current  of  chlorine'through  bromine,  and  con- 
densing the  disengaged  vapours  by  means  of  a  freezing  mixture. 

SECTION  IV. 

IODINE. 
Atom.  Num.  126—  Sijmb.  I—Sp.  gr.  4  948  water=l. 

Discovered  in  1812,  by  M.  Courtois,  a  manufacturer  of  saltpetre,  at 
Paris  ;  recognized  as  a  new  body,  by  M.  Clement,  in  1813,  and  after- 
wards shown  to  be  an  elementary  one,  by  Gay  Lussac  and  Davy.  The 


IODINE.  107 

name  is  derived  from  the  Greek  iodecz,  in  allusion  to  the  violet  colour 
-  of  its  vapour. 

PROPERTIES.  A  soft  and  friable  solid,  of  a  bluish-black  colour,  and 
metallic  lustre  ;  a  non-conductor  of  electricity  ;  produces  a  yellow 
stain  upon  the  skin  ;  smell  resembling  that  of  diluted  chlorine  ;  taste 
acrid  ;  is  extremely  volatile,  rising  into  a  rich  violet  coloured  vapour, 
at  a  temperature  of  beween  80  and  100°  F. ;  fuses  at  225°  F.,  and  en- 
ters into  ebullition  at  347°  F.  ;  is  sparingly  soluble  in  water,  but  read- 
ily so  in  alcohol  or  ether  ;  acts  energetically  upon  the  animal  system  ; 
destroys  vegetable  colours,  but  forms  a  blue  compound  with  starch  ; 
combines  with  phosphorus  and  various  other  substances. 

Iodine  is  very  volatile. — This  can  be  very  easily  shown  by  introducing 
into  a  retort  or  bolt  head,  a  small  portion  of  iodine,  and  applying  a 
gentle  heat.  The  violet  vapours  rise  and  fill  the  vessel :  upon  the  ap- 
plication of  cold  these  are  again  condensed. 

Is  sparingly  soluble  in  water. — Water  does  not  hold  more  than  1- 
TOOOths  of  its  weight  of  iodine  in  solution;  but  even  this  communi- 
cates a  brownish  tint.  The  proper  solvents  are  ether  and  alcohol.  It 
is  in  these  forms  that  it  is  often  employed  for  medicinal  purposes. 

Combines  with  phosphorus. — Phosphorus  brought  into  contact  with 
iodine  takes  fire,  if  the  experiment  is  performed  in  the  open  air  ;  but 
in  close  vessels  no  light  appears.  Iodine  combines,  also,  with  most  of 
the  other  non-metallic  combustibles,  and  with  the  metals,  forming  a 
class  of  compounds  denominated  Iodides  or  lodurets. 

Forms  a  blue  compound  with  starch. — This  is  a  most  delicate  test  for 
the  presence  of  iodine,  and  it  is  said  by  Prof.  Stromeyer,  that  a  liquid 
containing  1-450,000  of  its  weight  of  iodine,  receives  a  blue  colour 
from  starch.  Two  precautions  should  be  observed  to  ensure  success. 
First,  the  iodine  must  be  in  a  free  state,  for  it  is  the  iodine  alone  and 
not  any  of  its  compounds  which  unites  with  starch.  Secondly,  the 
solution  should  be  quite ^cold  at  the  time  of  adding  the  starch;  for 
boiling  water  decomposes  the  blue  compound  and  consequently  re- 
moves its  colour. 

NATIVE  STATE.  Iodine  has  been  discovered  in  a  great  number  of  the 
fuci,  which  grow  upon  the  sea  shores,  in  sponges,  in  various  mollus- 
cous animals,  and  in  sea  water  ;  and  it  has  been  found  by  Vauquelin, 
combined  with  silver,  in  South  America.  It  has  also  been  found,  in 
a  state  of  combination,  in  various  salt  springs  in  Europe  and  America. 

PREPARATION.  Lixiviate  powdered  kelp,  (the  semi-fused  ashes  of 
seaweed,)  with  cold  water.  Evaporate  the  lixivium  till  a  pellicle 
forms,  and  then  set  it  down  to  crystallize.  Evaporate  the  mother 
liquor  to  dryness,  and  pour  upon  the  mass  half  its  weight  of  sulphuric 
acid.  Apply  heat  to  this  mixture  in  an  alembic  to  which  a  receiver  is 
attached  ;  fumes  of  a  violet  colour  arise  and  condense  in  the  form  of 
opaque  crystals,  having  a  metallic  lustre,  which  are  to  be  washed  out 
of  the  head  of  the  alembic  with  a  small  quantity  of  water  and  quickly 
dried  upon  bibulous  paper. 

ADULTERATION.  Iodine  is  sometimes  adulterated  with  black  lead. 
This  may  be  detected  by  dissolving  the  substance  in  alcohol,  and  also 
by  subjecting  it  to  heat.  Black  lead  is  not  soluble  in  alcohol,  neither 
is  it  vaporized  by  heat. 

ACTION  ON  THE  ANIMAL  ECONOMY.  In  small  doses  iodine  is  employ- 
ed with  success  in  various  diseases,  but  in  larger  ones  it  excites  nausea 


108  IODINE. 

and  vomiting,  and  other  distressing  symptoms. — See  Magendie's  For- 
mulary and  Beck's  Med.  Juris.  484. 

REFERENCES.  Gay  Lussar,  Ann.  of  Phil.  iii.  106.  Van  Mons.  ibid.  429. 
Sir  H.  Davy,  Phil.  Trans.  1814,  and  Ann.  of  Phil,  iii,  and  \v.  Gay  Lus- 
sac's  Memoir  on  Iodine  and  its  compounds,  Ann.  de  Chim.  xci.  5,  and  in  Ann. 
of  Phil.  v.  101,  207,  296,  401,  vi.  124,  183.  Crystalline  form  of  Iodine, 
Branded  Jour.  v.  364,  and  Sill.  Jour,  xviii.  84.  Hobsoii's  Prize  Essay  on 
Iodine. 

COMPOUNDS    OP    IODINE  AND    OXYGEN. 

Two  compounds  of  iodine  and  oxygen  have  been  noticed  by  che- 
mists—the lodous  and  lodic  Adds.  The  former,  however,  as  we  shall 
presently  see,  is  involved  in  some  obscurity. 

lodous  Acid. 
Discovered  by  Professor  Sementini,  of  Naples,  in  1824. 

PROPERTIES.  An  oily  liquid,  having  a  disagreeable  odour ;  taste, 
acid,  and  astringent  ;  reddens  vegetable  blues  permanently,  without 
destroying  them;  is  rapidly  volatilized  at  212°  F.  arid  evaporates 
slowly  at  common  temperatures  ;  is  decomposed  by  sulphur ;  phos- 
phorus and  potassium  take  fire  as  soon  as  they  come  in  contact 
with  it. 

PREPARATION.  Equal  parts  of  iodine  and  chlorate  of  potassa  are 
to  be  triturated  together  in  a  glass  or  porcelain  mortar,  until  they 
form  a  fine  pulverulent  yellow  mass,  in  which  the  metallic  lustre 
of  the  iodine  is  no  longer  visible.  The  mixture  is  then  heated  in  a 
glass  retort,  and  as  soon  as  the  chlorate  begins  to  lose  oxygen,  iodous 
acid  rises  in  the  form  of  a  dense  white  vapour,  and  condenses  in  the 
neck  of  the  retort  into  a  yellow  liquid,  which  falls  in  drops  into  the  re- 
ceiver. 

It  is  asserted  by  M.  Wbhler  that  this  compound  does  not  consist 
of  iodine  and  oxygen,  but  of  chlorine  and  iodine.  This  has  led  to  new 
investigations  on  the  part  of  Sementini,  which  render  it  probable  that 
there  exists  both  iodous  acid  and  oxide  of  iodine. — Brandes  Jour. 
N.  8.  ii.  203. 

REFERENCES. — SementinVs  account,  see  Branded  Jour.  xvii.  381 — same 
work,  N.  S.  i.  477. 

lodic  Acid— Atom.  Num.  166—Symb.  5O+I. 

Discovered  about  the  same  time  by  Gay  Lussac  and  Sir  H.  Davy  ; 
by  the  latter  of  whom  it  was  termed  Oxiodine.  In  its  dry  state,  it 
constitutes  Anhydrous  lodic  Acid. 

PROPERTIES.  A  regular  crystalline  body  which  has  a  strong  astrin- 
gent sour  taste,  but  no  odour ;  density  greater  than  that  of  sulphuric 
acid  ;  is  fused  at  500°  F.  and  resolved  into  oxygen  and  iodine  ;  is  very 
soluble  in  water,  and  deliquesces  in  moist  air.  The  liquid  acid  thus 
formed,  reddens  vegetable  blue  colours,  and  afterwards  destroys  them. 
On  evaporating  the  solution,  a  thick  mass,  of  the  consistence  of  paste, 
is  left,  which  is  Hydrous  lodic  Acid,  and  from  which,  by  the  cautious 
application  of  heat,  the  water  may  be  expelled.  It  acts  powerfully  on 


IODINE.  109 

inflammable  substances;  with  charcoal,  sulphur,  sugar  and  similar 
combustibles,  forms  mixtures  which  detonate  when  heated  ;  combines 
with  bases  and  forms  a  class  of  bodies  denominated  lodates,  which  are 
analogous  to  the  chlorates. 

According  to  Mr.  Connel  this  acid  may  be  formed  by  digesting 
iodine  with  nitric  acid  over  a  spirit  lamp,  in  a  large  flask,  and  washing 
down  the  iodine  as  it  condenses  on  the  sides  of  the  flask. — [Jameson's 
Jour.  1831,  p.  72.]  The  process  recommended  by  Liebig  is  to  precipi- 
tate the  iodate  of  soda  by  chloride  of  barium  ;  to  every  nine  parts  of 
the  precipitate,  well  washed  and  dried,  to  add  two  of  sulphuric  acid 
diluted  with  ten  or  twelve  of  water,  to  boil  half  an  hour,  filter,  evapo- 
rate to  a  sirupy  consistence,  and  expose  it  to  the  air  for  several  days. 
Regular  transparent  crystals  are  formed  to  the  last  drop. — Johnston's 
Report  on  Chemistry. 

IODINE    AND    CHLORINE. 

Chloriodic  Add— Atom.  Num.  196-90—  Symb.  2C1+I. 

Discovered  by  Gay  Lussac  and  Sir  H.  Davy  ;  and  by  the  former 
called  Chloride  of  Iodine. 

PROPERTIES.  A  solid  compound,  of  an  orange  yellow  colour,  when 
the  iodine  is  fully  saturated  with  chlorine,  but  of  a  reddish  orange  if 
the  iodine  is  in  excess  ;  by  heat  is  converted  into  an  orange  liquid, 
which  yields  a  vapour  of  the  same  tint  on  increase  of  temperature  ;  de- 
liquesces in  the  open  air  and  dissolves  freely  in  water ;  forms  a  colour- 
less solution,  which  is  very  sour  to  the  taste,  and  reddens  vegetable 
blues,  but  afterwards  destroys  them. 

Possesses  acid  properties. — On  this  point  there  is  still  some  dispute. 
Davy  gave  the  compound  the  name  of  chloriodic  acid,  but  Gay  Lussac 
on  the  contrary,  conceives  that  the  acidity  of  its  solution  arises  from 
the  presence  of  muriatic  and  iodic  acids,  which  he  supposes  to  be  gene- 
rated by  the  decomposition  of  water.  The  opinion  of  Davy  is  most 
generally  received,  yet  this  compound  does  not  unite  with  alkaline 
substances,  a  fact  somewhat  difficult  of  explanation  upon  this  suppo- 
sition. 

PREPARATION.  This  compound  may  be  prepared  very  readily  by  the 
direct  union  of  chlorine  and  iodine. 


IODINE    AND    BROMINE. 

Bromides  of  Iodine. 

Bromine  and  iodine  act  readily  on  each  other  and  appear  capable 
of  uniting  in  two  proportions.  The  proto-bromide  is  a  solid,  converti- 
ble by  heat  in  a  reddish-brown  vapour,  which  in  cooling,  condenses 
into  crystals  into  the  same  colour,  and  of  a  form  resembling  that  of 
fern  leaves.  An  additional  quantity  of  bromine  converts  these  crys- 
tals into  a  fluid,  which,  in  appearance,  is  like  a  strong  solution  of 
iodine  in  hydriodic  acid.  This  compound  dissolves,  without  decom- 
position, in  water,  but  with  the  alkalies  yields  hydrobromic  and 
iodic  acids.  But,  as  is  remarked  by  Dr.  Turner,  the  existence  of  two 
bromides  of  iodine  can  scarcely  be  regarded  as  satisfactorily  estab- 
lished. 


110  HYDROGEN. 

SECTION   V. 

FLUORINE. 
Atom.  Num.  18-68.  Syml.  F. 

The  substance  to  which  this  name  is  applied  has  not  heretofore 
been  obtained  in  a  separate  state,  and  hence  the  properties  which 
are  peculiar  to  it  in  that  state,  are  entirely  unknown.  From  the 
nature  of  its  compounds  it  appears  to  belong  to  the  class  of  nega- 
tive electrics,  and  like  oxygen  and  chlorine,  to  have  a  powerful  affini- 
ty for  hydrogen  and  metallic  substances.  With  hydrogen  it  consti- 
tutes a  very  peculiar  acid,  the  Hydrofluoric  Acid,  which  I  shall  no- 
tice hereafter. 


CHAPTER  VII. 

ELECTRO-POSITIVE    BODIES. 

The  electro-positive  class  of  bodies,  includes  all  those  substances 
which  have  not  been  previously  described.  They  are  sometimes  also 
called  Combustibles.  As  they  are  quite  numerous,  it  will  be  convenient 
to  divide  them  into, 

1.  Those  which  are  NON-METALLIC. 

2.  Those  which  are  METALLIC. 

The  non-metallic  simple  electro-positive  bodies  are,  HYDROGEN,  NI- 
TROGEN, SULPHUR,  PHOSPHORUS,  CARBON,  BORON  and  SELENIUM. 

SECTION  I. 

HYDROGEN. 
Atom.  Num.  1—Symb.  H—  Sp.  gr.  0-0694  air=l. 

First  proved  to  be  a  distinct  gas  by  Cavendish,  in  1766.  It  derives 
its  name  from  the  Greek  words  signifying  the  generator  of  water.  It 
is  also  sometimes  called  Inflammable  Air. 

PROPERTIES.  A  colourless  gas,  having  neither  odour  nor  taste, 
when  perfectly  pure  ;  a  powerful  refractor  of  light ;  the  lightest  body 
in  nature  ;  is  sparingly  absorbed  by  water  ;  inflammable  in  an  eminent 
degree  ;  cannot  support  respiration  nor  combustion  ;  detonates  when 
combined  with  oxygen  and  fired  ;  takes  fire  when  brought  into  contact 
with  a  platinum  sponge  ;  produces  an  intense  degree  of  heat  when 
burned  under  pressure. 

Hydrogen  gas  is  destitute  of  odour. — This  is  only  true  of  the  most 
pure  form  of  this  substance  ;  but  as  commonly  obtained,  it  has  a  slight- 
ly disagreeable  smell. 


HYDROGEN.  Ill 

Is  the  lightest  body  in  nature. — 100  cubic  inches  of  this  gas  weigh 
2'118  grains  at  mean  pressure  and  temperature  ;  it  is  16  times  lighter 
than  oxygen  gas  ;  200,000  times  lighter  than  mercury,  and  300,000 
times  lighter  than  platinum. 

The  extreme  levity  of  hydrogen  can  be  shown  by  fitting  soap  bub- 
bles with  it,  which  will  be  found  to  ascend  rapidly.  Hence  balloons 
are  now  filled  with  this  gas. 

Is  highly  inflammable. — The  inflammability  of  hydrogen  can  be 
shown  in  various  ways. 

A  candle  kindles  ajar  of  it,  but  is  itself  extinguished  by  immersion 
into  the  gas,  and  is  relighted  if  the  wick  again  touch  the  flame. 

To  a  bottle  containing  the  materials  for  hydrogen  gas  attach  a  tube. 
if  the  common  air  be  now  allowed  to  escape,  and  the  gas  kindled  at 
the  orifice  of  the  tube,  the  jet  is  called  the  philosophic  candle. 

When  a  stream  of  hydrogen  gas  is  burned  under  a  tube  of  from  12  to 
20  inches  long,  musical  sounds  are  produced,  owing  to  the  succession 
of  explosions  which  take  place. — Faraday  in  Brandes  Jour.  v.  274. 

Hydrogen  gas,  when  combined  in  the  proportion  of  2  parts  to  1  part 
of  oxygen,  explodes  violently  on  contact  with  the  flame  of  a  candle. 
The  same  thing  takes  place,  though  in  an  inferior  degree,  if  the  hydro- 
gen be  mixed  with  atmospheric  air,  in  the  proportion  of  1  of  hydro- 
gen to  about  3  of  air.  In  each  of  these  cases  the  product  of  combus- 
tion is  water.  These  experiments  may  be  performed  in  a  strong  glass 
vial  or  metallic  air  pistol,  and  the  explosion  is  equally  produced  by 
the  electric  spark  as  by  the  contact  of  flame,  or  by  a  solid  body  healed 
to  bright  redness. 

It  has  been  discovered  by  M.  Biot  that  a  mixture  of  hydrogen  and 
oxygen  gases  may  be  made  to  explode  by  mechanical  compression. 
A  mixture  of  these  two  gases,  was  introduced  into  a  strong  metallic 
syringe,  furnished  with  a  glass  bottom,  and  a  sudden  stroke  given  to 
the  piston,  an  extremely  brilliant  light  appeared,  accompanied  with 
a  loud  detonation  ;  and  the  glass  bottom  was  forcibly  driven  out.  The 
repetition  of  this  experiment,  it  is  obvious,  must  be  attended  with 
some  difficulty  and  danger. — Nicholson'*  Jour.  8vo.  xii.  212.  Henry's 
Chem.  i.  262. 

Does  not  support  combustion  nor  respiration. — The  former  of  these 
has  already  been  shown,  under  the  last  article.  An  animal  soon  per- 
ishes, when  confined  in  it.  Death  ensues  from  deprivation  of  oxy- 
gen, rather  than  from  any  noxious  quality  of  the  hydrogen,  since  an 
atmosphere  composed  of  a  due  proportion  of  oxygen  and  hydrogen 
£ases  may  be  respired  without  inconvenience.  It  appears,  however, 
according  to  the  trials  of  Mess.  Allen  and  Pepys,  to  have  the  curious 
property  of  throwing  the  animal  into  a  profound  sleep. 

Takes  Jire  when  brought  into  contact  with  spongy  platinum. — This 
singular  fact  was  discovered  by  Professor  Dobereiner  of  Jena,  in  1824. 
For  the  purpose  of  exhibiting  this  experiment,  let  platinum  sponge  be 
prepared,  by  dissolving  platinum  in  nitromuriatic  acid,  and  then  pre- 
cipitating it  by  means  of  ammonia.  If  a  jet  of  hydrogen  from  some 
orifice,  and  under  hi^h  pressure,  be  brought  into  contact  with  this 
sponge,  it  instantly  becomes  red  hot,  and  the  gas  soon  takes  fire. 
This  has  been  applied  in  various  ways  to  the  construction  of  lamps 
for  producing  instantaneous  light.  Several  metallic  bodies  produce 
the  same  effect ;  especially  palladium,  rhodium  and  iridium. 

Produces  an  intense  degree  of  heat,  when  burned  under  pressure. — Iron 
wire  can  readily  be  burned  by  a  stream  of  hydrogen  gas,  under  strong 
pressure. 


112  HYDROGEN. 

But  the  most  intense  degree  of  heat  is  occasioned  by  the  combustion 
of  a  mixture  of  hydrogen  and  oxygen  gases,  as  it  issues  from  a  very 
small  jet.  This  apparatus,  commonly  known  as  the  Compound  or  Oxy- 
kydrogen  blowpipe,  and  first  employed  by  Dr.  Hare  of  Philadelphia,  has 
been  variously  modified  by  Dr.  Clarke,  Mr.  Newman,  Dr.  Wollaston. 
and  others.  These  modifications  were  all  proposed  for  the  purpose  of 
preventing  the  recession  of  the  flame  and  the  consequent  explosion  of 
the  mixed  gases  :  an  object  which  has  been  most  happily  attained  by 
the  safety  tube  lately  proposed  by  Mr.  Hemming.  It  consists  of  a 
brass  cylinder  about  six  inches  long  and  three  fourth  of  an  inch  in  di- 
ameter, filled  with  very  fine  brass  wire,  in  length  equal  to  that  of  the 
tube.  A  metallic  rod  l-8th  of  an  inch  thick  is  then  forcibly  driven 
through  the  centre  of  the  bundle  of  wires  in  the  tube,  so  as  to  wedge 
them  firmly  together.  The  interstices  between  the  wires  thus  consti- 
tute very  fine  metallic  tubes,  the  cooling  and  conducting  powers  of  which 
are  so  great  as  entirely  to  intercept  the  passage  of  flame.  So  com- 
pletely effectual  is  this  contrivance  that  the  wells  and  reservoirs  ordi- 
narily employed  may  be  dispensed  with  and  the  mixed  gases  supplied 
from  a  common  bladder  under  the  arm. — Reports  of  the  British  Associa- 
tion for  1832. 

A  very  intense  heat,  quite  sufficient  for  most  purposes,  may  be  safe- 
ly and  easily  procured  by  causing  a  jet  of  oxygen  gas  to  pass  through 
the  flame  of  a  spirit  lamp  as  proposed  by  Mr.  Marcet.  [./tfnn.  of  Phil. 
ii.  99.]  Or  still  better,  by  substituting  the  flame  of  coal  gas  for  that 
of  alcohol,  upon  the  plan  of  Mr.  Daniell. — Phil.  Mag.  and  Ann.  for 
1833. 

In  all  the  above  cases  of  combustion  the  product  is  water,  and  the 
heat  produced  can  be  accounted  for  upon  the  general  principles  which 
have  been  laid  down,  viz.  that  these  gaseous  substances,  in  assuming 
the  liquid  form,  give  out  the  caloric  with  which  they  are  combined. 

PREPARATION.     Hvdrogen  gas  may  be  easily  procured  in  two  ways. 

1.  By  passing  the  vapour  of  water  over  metallic  iron  heated  to  red- 
ness.    This  is  done  by  putting  iron  wire  into  a  gun  barrel,  open  at 
both  ends,  to  one  of  which  is  attached  a  retort,  containing  pure  water, 
and  to  the  other  a  bent  tube.     The  gun  barrel  is  placed  in  a  furnace, 
and  when  it  has  acquired  a  full  red  heat,  the  water  in  the  retort  is 
made  to  boil  briskly.     The  gas,  which  is  copiously  disengaged  as  soon 
as  the  steam  comes  in  contact  with  the  glowing  iron,  passes  along  the 
Uent  tube,  and  may  be  collected  in  convenient  vessels,  by  dipping  the 
iree  extremity  of  the  tube  into  the  water  of  a  pneumatic  trough. 

2.  By  putting  pieces  of  iron  or  zinc  into  dilute  sulphuric  acid,  form- 
ed of  one  part  of  strong  acid  to  four  or  five  of  water — five  are  generally 
preferred.     But  in  neither  of  these  cases  is  the  hydrogen  absolutely 
pure  ;  it  has  an  offensive  odour,   derived  from  impurities  in  the  iron 
and  zinc,  as  they  are  met  with  in  commerce.    All  these  impurities,  ex- 
cept carburetted  hydrogen,  may  be  removed  by  passing  the  gas  through 
a  solution  of  pure  potassa.     If  hydrogen  of  great  purity  is  desired,  dis- 
tilled zinc  should  be  employed. 

In  both  of  the  above  cases  water  is  decomposed  ;  the  oxygen  com- 
bines with  the  metal  and  forms  an  oxide,  and  the  hydrogen  escapes  in 
a  gaseous  form. 


HYDROGEN.  113 

REFERENCES. — Cavendish,  experiments  on  Factitious  Air,  Phil.  Trans. 
1766.  Action  of  Hydrogen  upon.  Platinum,  fyc.  Thenard,  Traite  de  Chint. 
i.  338.  An  elaborate  account  of  Dr.  Clarke's  Compound  Blow-pipe,  and-of 
its  effects  upon  numerous  refractory  substances^  is  given  in  the  appendix  to 
the  Life  of  Dr.  Ed.  D.  Clarke.  For  papers  on  Dr.  Hare's  Blow-pipe,  see 
SWwatfs  Jour.  1 98,  ii.  181,  281. 

HYDROGEN    AND    OXYGEN. 

Two  compounds  of  these  bodies  are  at  present  known,  viz.  the  Pro- 
toxide or  water ,  and  the  Deutoxide. 

PROTOXIDE  OP  HYDROGEN  OR  WATER. 

Atom.  Num.  9—Symb.  O+H—Sp.  gr.  1. 

PROPERTIES.  A  well  known  liquid,  transparent,  colourless,  inodor- 
ous and  tasteless  ;  compressible,  by  very  strong  pressure  ;  elastic  ;  a 
bad  conductor  of  electricity,  and  changed  by  the  application  of  heat 
into  vapour,  by  the  abstraction  of  it  into  ice.  Its  specific  gravity  is  1, 
the  density  of  all  solid  and  liquid  bodies  being  referred  to  it  as  a  term 
of  comparison.  One  cubic  inch,  at  60°  F.  and  30  Bar.  weighs  252.525 
grains,  so  that  it  is  828  times  heavier  than  atmospheric  air. 

The  following  are  among  the  most  important  chemical  properties  of 
water. 

I.  It  contains  air. — This  may  be  shown  by  placing  a  glass  vessel  of 
water,  fresh  from  a  spring,  or  even  of  distilled  water  that  has  been  ex- 
posed a  few  days  to  the  atmosphere,  under  the  receiver  of  an  air  pump. 
During  the  exhaustion  of  the  receiver,  bubbles  of  air  will  be  seen  to  as- 
cend very  plentifully.  Much  air  escapes  also  from  water  during  boil- 
ing, and  may  be  collected  by  a  proper  apparatus ;  but  it  again  absorbs 
it  when  exposed  to  the  atmosphere. 

Water  which  has  been  deprived  of  its  air,  by  long  boiling,  possesses 
the  pi-operty  of  absorbing  every  gas,  though  the  quantity  which  it  is 
capable  of  absorbing  varies  considerably  with  respect  to  the  different 
gases. 

Water  absorbs,  at  the  mean  pressure  and  temperature,  according  to 
the  recent  investigations  of  Henry  and  Dalton, 

Of  carbonic  acid  gas,         .  its  own  bulk. 

Sulphuretted  hydrogen,     ....  do. 

Nitrous  oxide, do. 

Olefiantgas,  l-8th. 

Oxygen  gas, l-27th. 

Nitrous  gas,  .....  do. 

Carburetted  hydrogen,      ....  do. 

Carbonic  oxide, l-64th. 

Nitrogen  gas,  do. 

Hydrogen  gas, do. 

IHenry.  i.  276,  Ann.  of  Phil.  vi.  340,  vii.  215.] 

2.  Ft  enters  into  combination  with  various  bodies. — Sometimes  it  is 
contained  in  a  variable  ratio,  as  in  solution  ;  at  others  it  forms  a  mere 
accidental  ingredient,  as  in  common  salt  or  sulphate  of  potassa.  In 


114  HYDROGEN. 

many  instances,  however,  it  unites  in  a  fixed  definite  proportion  ;  as  is 
the  case  in  its  combination  with  several  of  the  acids,  and  metallic 
oxides  and  of  all  the  salts  that  contain  water  of  crystallization.  These 
compounds  are  termed  Hydrates ;  and  in  some  of  them  the  water  is 
held  by  so  powerful  an  affinity  as  not  to  be  separated  by  a  very  high 
temperature.  The  pure  alkalies  potassa  and  soda,  retain,  for  example, 
even  after  fusion,  about  one- fifth  their  weight  of  water,  of  which  they 
can  only  be  deprived  by  some  body  having  a  stronger  affinity  for  the 
alkali. 

Water  is  contained  in  the  atmosphere,  even  during  the  driest  weather. — 
Expose  to  the  air.  in  a  shallow  vessel,  a  little  subcarbonate  of  potassa, 
or  common  salt  of  tartar ;  in  a  few  days  it  will  have  become 
moist,  or  deliquiated,  and  will  have  increased  considerably  in  weight. 
So  also  when  sulphuric  acid  is  added  to  common  salt,  dense  white 
fumes  are  given  out,  in  consequence  of  the  combination  of  the  muri- 
atic acid  with  the  moisture  in  the  air. 

There  are  two  different  theories  of  the  state  in  which  water  pxists 
in  the  atmosphere,  and  in  other  gases.  By  most  chemists  it  has  been 
considered  as  united  to  air  by  chemical  affinity,  and  when  abstracted 
by  other  bodies,  the  effect  has  been  ascribed  to  the  superior  affinity  of 
those  bodies  for  water.  According  to  Mr.  Dalton,  however,  aqueous 
vapour  constitutes  a  distinct  and  independent  atmosphere,  the  elastic 
force  of  which  forms,  at  different  temperatures,  different  proportions 
of  the  elastic  force  of  the  whole  ;  for  example,  at  the  temperature  of 
65°  F.  it  gives  to  air  l~50th  of  its  elasticity.  Hence,  a  volume  of  air 
or  gas  at  any  temperature,  saturated  with  moisture,  contains  as  much 
steam  as  would  exist,  at  that  temperature,  in  a  vacuum  of  equal  ca- 
pacity. This  view,  confirmed  by  the  experiments  of  Gay  Lussac,  is 
much  more  probable  than  that  which  explains  the  phenomena  by 
chemical  affinity  ;  and  it  is  supported  especially  by  the  fact  that  the 
absorption  of  caloric  is  precisely  the  same  in  amount  in  spontaneous 
as  in  forced  evaporation.  It  steers  clear  also  of  the  inconsistency  at- 
tending the  supposition  that  the  vapour  contained  in  the  atmosphere, 
at  ordinary  temperatures,  is  in  a  different  state  from  that  existing  in  a 
Toricellian  vacuum  ;  and  again,  that  water  below  "212°  F.  is  chemi- 
cally combined  with  the  atmosphere,  and  above  212°  assumes  a  new 
form  and  becomes  a  distinct  elastic  fluid,  called  steam.  It  is  certainly 
much  more  reasonable  to  suppose  that  water,  whenever  it  exists  as  an 
elastic  fluid,  whether  distinct  from,  or  mixed  with  others,  is  maintain- 
ed as  such  by  one  and  the  same  cause,  viz.  by  its  constituent  caloric,  and 
not  by  chemical  solution,  in  any  gas  or  mixture  of  gases. — Henry,  i. 
278. 

The  purest  water  that  can  be  found  as  a  natural  product,  is  produc- 
ed by  melting  freshly  fallen  snow,  or  by  receiving  rain  in  clean  vessels 
at  a  distance  from  houses.  But  this  water  is  not  absolutely  pure  ;  for 
if  placed  under  the  exhausted  receiver  of  an  air-pump,  or  boiled  brisk- 
ly for  a  few  minutes,  bubbles  of  gas  escape  from  it.  The  air  obtained 
in  this  way  from  snow  water,  is  much  richer  in  oxygen  gas  than  atmos- 
pheric air.  According  to  the  experiments  of  Gay  Lussac  and  Humboldt, 
it  contains  34'8  per  cent  of  oxygen,  and  the  air  separated  by  ebullition 
from  rain-water  contains  32  per  cent  of  that  gas.  All  water  which  has 
once  fallen  on  the  ground,  becomes  impregnated  with  more  or  less  of 
earthy  or  saline  matters,  and  it  can  be  separated  from  them  only  by 
distillation.  The  distilled  water  thus  obtained,  and  preserved  in  clean 
well  slopped  vessels,  is  absolutely  pure.  In  this  state  it  is  employed 
for  the  purposes  of  analysis  and  in  pharmacy. 


HYDROGEN.  115 

Ice.  When  water  is  exposed  to  the  action  of  cold,  it  condenses 
more  and  more,  until  it  reaches  the  temperature  of  about  39 D  F.  ;  after 
which  it  expands  to  the  point  of  congelation.  Hence  ice  is  lighter 
than  water  :  its  specific  gravity  is  not  far  from  0-93.— [See  page  48.] 

Ice  exists  naturally  at  the  poles,  even  in  the  midst  of  the  sea,  at  all 
times.  Under  other  parallels  it  is  found  in  this  state  only  at  a  certain 
elevation,  which  increases  as  we  proceed  from  the  poles  to  the  equa- 
tor. The  masses  of  snow  which  accumulate  on  the  summits  of  moun- 
tains, being  alternately  melted  and  congealed,  become  at  last  changed 
by  this  process  into  solid  ice,  often  grouped  and  fashioned  by  such 
irregular  action  into  the  most  fantastic  shapes,  constituting  what  are 
denominated  Glaciers.  In  its  native  seat,  this  icy  belt  acquires  con- 
tinual additions  to  its  height,  till  the  accumulating  pressure  at  last 
tears  the  mass  from  its  base  and  precipitates  its  dissevered  fragments 
to  a  lower  level.  In  its  new  position,  below  the  inferior  boundary  of 
congelation,  the  enormous  pile  suffers,  on  the  whole,  a  very  gradual 
thaw,  which  is  sometimes  protracted  for  several  centuries,  and  gives 
birth  to  streams  of  greater  or  less  magnitude.  Meanwhile  in  the  high- 
er magazine,  another  icy  belt  is  again  slowly  collecting,  which  will  in 
due  time  repeat  the  succession,  arid  maintain  the  eternal  circle  of  pro- 
duction and  decay. — See  Art.  Climate,  in  Suppl.  Encycl.  Brit. 

Vapour  or  steam. — If  water  be  exposed  to  the  heat  of  212°,  the  ba- 
rometer being  30,  it  is  converted  into  a  transparent  gas,  which  is  cal- 
led aqueous  vapour  or  s!eam}  the  bulk  of  which  is  about  1700  times 
greater  than  that  of  water.  Under  a  diminished  pressure,  however, 
water  boils  below  the  temperature  of  212°,  while  on  the  contrary, 
when  the  pressure  is  increased,  the  boiling  point  is  higher.  In  every 
case,  therefore,  the  tension  of  the  vapour  depends  upon  the  tempera- 
ture. A  table  has  been  constructed  by  Mr.  Dalton,  to  show  the  elastic 
force  of  vapour  at  every  degree  of  the  thermometer. 

The  boiling  of  water  is  influenced  in  some  degree  also  by  its  purity. 
Thus,  if  it  contains  a  portion  of  common  salt  in  solution,  its  specific 
gravity  will  be  increased,  and  under  the  same  pressure  the  boiling  point 
will  be  several  degrees  higher  than  when  the  water  is  pure. 

Composition  of  water.  This  may  be  determined  by  analysis  andsyn- 
thesis.  1st,  by  Synthesis. 

When  two  volumes  of  hydrogen  are  mixed  with  one  volume  of  ox- 
ygen gas,  and  the  mixture  inflamed  in  a  proper  apparatus  by  the  elec- 
tric spark,  the  gases  totally  disappear,  and  the  interior  of  the  vessel  is 
covered  with  drops  of  pure  water,  equal  in  weight  to  that  of  the  gases 
consumed.  The  same  effect  is  also  produced  by  burning  hydrogen  in 
an  atmosphere  of  pure  oxygen  gas.  An  apparatus  for  producing  water 
by  the  electric  spark,  is  figured  in  the  Library  of  Useful  Knowledge, 
art.  Chemistry. 

It  should  be  recollected  that  every  gas  is  a  compound  of  gravitating 
matter  with  heat,  and  perhaps  electricity  and  light.  In  the  above  ex- 
periments the  bases  of  these  gases  combine  to  form  water,  the  impon- 
derable ingredients  having  for  the  most  part  escaped  during  the  com- 
bustion. 

2.  The  composition  of  water  may  be  proved  analytically  as  follows  : 

By  exposing  pure  water  to  the  action  of  the  Voltaic  battery,  it  is  re- 
solved into  two  volumes  of  hydrogen,  disengaged  at  the  negative  pole, 
arid  one  volume  of  oxygen,  disengaged  at  the  positive  ;  and  hence  the 
atomic  constitution  is  such  as  has  been  stated  above.  Water  may  also 
be  resolved  into  its  elements  by  passing  its  vapour  over  red  hot  iron. 


116  HYDROGEN. 

when  the  oxygen  combines  with  the  iron  and  the  hydrogen  is  liberated 
in  the  gaseous  form. 

REFERENCES.  TlienarvTs  Chem.  ii.  2.  Berzelius*s  very  elaborate  account^ 
Trait,  de  Chim.  i.  397.  Parkers  Chemical  Essays,  v.  4. 

Deutoxide  or  Peroxide  of  Hydrogen — Atom.  Num.  17 — Symb. 
2O+ H— Sp.  gr.  1-452  water=l. 

A  singular  compound  discovered  by  M.  Thenard,  in  1818.  Some- 
times also  called  Oxygenized  Water. 

PROPERTIES.  A  colourless  transparent  liquid,  without  odour ;  it 
whitens  the  skin  when  applied  to  it,  and  even  destroys  its  texture  if 
the  application  be  long  continued  ;  possesses  bleaching  properties  ;  is 
slowly  volatilized  in  vacuo,  and  hence  its  vapour  is  much  less  elastic 
than  that  of  water  ;  it  has  not  been  congealed  by  any  degree  of  cold 
hitherto  applied  to  it. 

The  most  remarkable  property  of  the  deutoxide  of  hydrogen  is  the 
facility  with  which  it  can  be  decomposed.  A  temperature  of  58°  F. 
is  sufficient  to  decompose  it  and  to  liberate  oxygen  gas  in  great  abun- 
dance. The  action  of  heat  varies  with  the  degree  of  concentration. 
Seven  or  eight  grains  of  the  sp.  gr.  1*452,  when  suddenly  heated,  are 
sufficient  to  occasion  a  violent  explosion  ;  and  therefore  to  obtain 
safely  the  whole  of  its  excess  of  oxygen  above  that  constituting  wa- 
ter, it  is  necessary  before  applying  heat,  to  dilute  it  with  about  20  parts 
by  weight  of  water. 

This  substance  is  powerfully  acted  on  by  many  of  the  metals  and 
metallic  oxides.  Tin,  iron,  antimony  and  tellurium  bring  it  back  ra- 
pidly to  the  state  of  water.  Gold,  platinum  and  silver,  when  finely 
divided  and  added  to  it,  liberate  its  oxygen,  without  themselves  un- 
dergoing any  change.  Arsenic,  tungsten,  potassium,  &c.  liberate  one 
part  of  the  oxygen  and  absorb  the  rest.  It  is  also  decomposed  by  seve- 
ral of  the  metallic  protoxides,  as  those  of  iron,  tin,  manganese,  &c. ; 
and  the  peroxides  of  silver,  lead,  mercury,  gold,  and  some  others  act 
upon  it  with  great  energy,  exciting  an  intense  heat  accompanied  with 
a  kind  of  explosion.  On  the  contrary,  the  acids  have  the  property  of 
rendering  it  a  more  stable  compound. 

PREPARATION.  To  obtain  this  substance  it  is  necessary  to  employ 
the  Peroxide  of  Barium,  a  compound  which  will  be  described  under 
the  article  Barium.  This  compound  when  acted  upon  by  liquid  mu- 
riatic acid,  abandons  part  of  its  oxygen,  and  is  reduced  to  the  state  of 
protoxide,  which  unites  with  the  muriatic  acid,  while  the  oxygen 
unites  with  the  water.  Sulphuric  acid,  added  to  the  compound  fluid, 
carries  down  the  baryta  and  sets  muriatic  acid  at  liberty,  which  is 
ready  to  act  upon  a  fresh  quantity  of  the  peroxide  of  barium.  This 
operation  may  be  several  times  repeated,  and  at  each  repetition  the 
water  becomes  charged  with  an  additional  quantity  of  oxygen.  When 
the  process  has  been  carried  far  enough,  sulphate  of  silver  is  added,  to 
precipitate  the  free  muriatic  acid,  which  it  replaces  by  a  quantity  of 
free  sulphuric  acid  ;  but  the  latter  is  easily  separated  by  adding  a  due 
proportion  of  baryta.  This  is  a  very  general  outline  of  the  process, 
which  requires  for  its  success  several  precautions,  and  especially  the 
greatest  attention  to  the  purity  of  the  peroxide  of  barium.  Minute 
directions  are  given  by  Thenard  in  the  original  paper. 


HYDROGEN.  117 

REFERENCES.  Ann.  deChim.  et  de  Ph.  viii.  ix.  Ann.  of  Phil.  xiii.  xiv. 
XY.'awoJ  Branded  Jour.  vi.  150,  379 — viii.  114,  154.  Thenard  ii.  42.  Ber- 
zelius,  i.  451,  under  the  name  of  Sur-oxide  hydrique.  I '"or  Dr.  Thomson's 
views  concerning  the  action  of  the  metals  and  metallic  oxides  upon  the  above 
compound,  see  his  Inorganic  Chemistry ,  i.  43. 

HYDROGEN    AND    CHLORINE.] 

Hydrochloric  or  Muriatic  Add — Atom.  Num.  3645 — Symb. 
Cl+H—  Sp.  gr.  1-269  air=l. 

Discovered  by  Priestley  in  1772,  and  for  a  long  time  known  under 
the  names  of  Spirit  of  Salt  and  of  Marine  Acid. 

PROPERTIES.  A  colourless  gas,  of  a  pungent  odour  and  acid  taste  ; 
extinguishes  burning  bodies,  and  is  quite  irrespirable,  exciting  violent 
spasm  of  the  glottis  ;  produces  a  white  cloud  when  brought  into  con- 
tact with  common  air,  owing  to  its  union  with  the  aqueous  vapour 
always  present  in  the  atmosphere  ;  is  decomposed  by  being  mixed 
with  oxygen  and  submitted  to  the  action  of  electricity  ;  rapidly  ab- 
sorbed by  water,  forming  liquid  muriatic  acid,  under  a  pressure 
of  40  atmospheres  ;  at  the  temperature  of  50°  F.  it  is  liquid ;  it 
combines  with  bases  forming  a  class  of  salts  called  Muriates  or  Hy- 
drochlorates. 

1.  It  extinguishes  a  lighted  taper. — Before  the  flame  goes  out,  the  up- 
per part  of  it  assumes  a  greenish  hue,  the  cause  of  which  has  not 
yet  been  explained.     A  white  vapour  also  surrounds  the  extinguished 
wick,  owing  to  the  combination  of  water  produced  by  the  combustion 
of  the  candle,  with  the  muriatic  acid  gas. 

2.  It  is  decomposed  by  electricity. — When  muriatic  acid  gas  is  sub] 
jected  to  the  action  of  a  galvanic  battery,  it  is  readily  decomposed, 
hydrogen  appearing  at  the  negative,  and  chlorine  at  the  positive  pole. 

It  is  also  decomposed  by  ordinary  electricity.  The  decomposition, 
however,  is  incomplete  ;  for  though  one  electric  spark  resolves  a  por- 
tion of  the  gas  into  its  elements,  the  next  shock  in  a  great  measure 
effects  their  reunion.  It  is  not  affected  by  oxygen  under  common  cir- 
cumstances ;  but  if  a  mixture  of  oxygen  and  muriatic  acid  gases  is 
electrified  the  oxygen  unites  with  the  hydrogen  of  the  muriatic  acid  to 
form  water,  and  chlorine  is  set  at  liberty. — Henry,  Phil.  Trans.  1812 
and  1824. 

3.  Some   of  the   metals  effect  its  partial  decomposition. — Potassium, 
by  being  heated  in  muriatic  acid  gas,  liberates  one  third  of  its  volume 
of  hydrogen.     Heated  zinc  and  tin  disengage  a  volume  of  hydrogen 
equal  to  one  half  that  of  the  muriatic  acid  gas,  and  chlorides  of  those 
metals  are  obtained.— Davy,  Phil.  Trans.  1810. 

4.  It  is  rapidly  absorbed  by  water. — A  drop  or  two  of  water  admit- 
ted to  a  large  jar  full  of  muriatic  acid  gas,   causes  the  whole  instantly 
to  disappear.     And  on  opening  a  long  wide  jar  filled  with  it,  under 
water,  the  absorption  of  the   gas  takes  place  so  instantaneously,  that 
the  water  is  forced  up  into  the  jar  with  the  same  violence  as  into  a 
vacuum.     When  a  piece  of  ice  is  put  into  a  jar  full  of  the  gas,  con- 
fined over  mercury,  the  ice  liquifies  on  the   instant,  and  the  whole  of 
the  gas  disappears  in  the  course  of  a  few  seconds. 


118  HYDROGEN. 

NATIVE  STATE.  Muriatic  acid  is  one  of  the  gaseous  substances 
which  issue  from  the  craters  of  volcanoes.  It  has  also  been  found  by 
Humboldt  in  a  number  of  warm  springs  in  Mexico. 

PREPARATION.     This  may  be  effected  in  various  ways. 

1.  If  a  phial  be  entirely  filled  with  a  mixture  of  chlorine  and  hydro- 
gen gases  in  equal  proportions,  and  a  well  ground  stopper  be  intro- 
duced, no  action  takes  place,  provided  light  is  carefully  and  complete- 
ly excluded,  even  by  standing  some  time  ;  but,  on  applying  a  lighted 
taper,  or  on  passing  an  electric  spark  through  the  mixture,  the  gases 
immediately  explode. 

2.  Let  a  stout  and  well  stopped  phial,  capable  of  holding  three  or 
four  ounce  measures,  be  filled  over  water  with  equal  volumes  of  chlo- 
rine and  hydrogen  gases,  and  a  ground  stopper  introduced.     Expose  it 
to  the  ordinary  day  light,  guarding  it  from  the  direct  rays  of  the  sun, 
and  in  twelve  or  fourteen  hours  the  colour  of  the  chlorine  will  have 
disappeared  ;  and  on  withdrawing  the  stopper  under  water,  the  phial 
will  be  immediately  filled  with  that  fluid. 

3.  If  the  experiment  be  repeated,  with  this  difference  that  the  phial 
is  exposed  to  the  direct  rays  of  the   sun,  the  combination  will  take 
place  rapidly,  arid  a  detonation  will  ensue,  which  will  probably   drive 
out  the  stopper.     But  if  this  should  not  happen,  the  stopper  may  be 
removed  under  water,  which  will  ascend  and  completely  fill  the  bottle. 
Prof.  Silliman  however  has  related  the  accidental  explosion  of  a  mix- 
ture of  these  gases,  in  the  quantity  that  filled  a  Florence  flask,  not 
only  when  no  direct  solar  light  fell  upon  it,  but  when  the  diffuse  light 
of  day  was  rendered  more  feeble  than  common  by  a  thick  snow  storm. 
[Amcr.  Jour.  iii.  342.]     This  fact  serves  as  a  caution  against  mixing 
the  two  gases  in  considerable  quantities. 

Mr.  Brande  found  [Phil.  Trans.  1820]  that  the  intense  light,  issuing 
from  charcoal  points  connected  with  a  powerful  galvanic  battery,  was 
as  effectual  as  solar  light  in  acting  on  hydrogen  and  chlorine  gases  and 
causing  them  to  detonate  ;  but  he  could  not  produce  an  analogous  ef- 
fect by  any  other  terrestrial  light.  The  moon's  rays,  also,  he  found  to 
foe  quite  inefficient  on  a  mixture  of  these  two  gases. 

To  obtain  muriatic  acid  in  sufficient  quantity  for  the  exhibition  of 
its  properties,  the  direct  combination  of  hydrogen  and  chlorine  is  not 
an  eligible  process.  It  may  be  procured  more  conveniently  as  follows  : 

1.  By  putting  an  ounce  of  strong  liquid  muriatic  acid  into  a  glass 
flask  or  retort,  and  heating  it  by  means  of  a  lamp  till  the  liquid  boils. 
Pure  muriatic  acid  gas  is  freely  evolved,  and  may  be  collected   over 
mercury. 

2.  By  adding  concentrated  sulphuric  acid  to  an  equal  weight  of  com- 
mon salt,  in  a  tubulated  retort  or  gas  bottle.     Brisk  effervescence  en- 
sues at  the  moment  of  making  the  mixture,  and  on  the  application  of 
heat  a  large  quantity  of  muriatic  acid  gas  is  disengaged. 

In  the  first  process  muriatic  acid,  previously  dissolved  in  water,  is 
simply  expelled  from  the  water  by  increased  temperature.  In  the 
second,  a  portion  of  the  water  contained  in  the  liquid  sulphuric  acid 
is  resolved  into  its  elements,  the  hydrogen  unites  with  the  chlorine  of 
the  common  salt,  forming  muriatic  acid,  which  escapes  in  the  form  of 
gas ;  while  soda  is  generated  by  the  combination  of  oxygen  with  the 
sodium,  which  combines  with  the  sulphuric  acid  and  forms  sulphate  of 
soda.  The  water  contained  in  the  liquid  sulphuric  acid  is  therefore 


HYDROGEN.  119 

essential  to  the  success  of  the  operation.  The  affinities  which  deter- 
mine the  change  are  the  attraction  of  chlorine  for  hydrogen,  of  sodium 
for  oxygen,  and  of  soda  for  sulphuric  acid. 

Liquid  muriatic  add. — The  liquid  muriatic  acid  may  be  obtained  by 
passing  a  current  of  the  gas  into  water  as  long  as  it  is  absorbed.  A 
considerable  increase  of  temperature  takes  place  during  the  absorption^ 
and  therefore  the  apparatus  should  be  kept  cool  by  ice.  Sir  H.  Davy 
states  that  water,  at  the  temperature  of  40J  F.  absorbs  480  times  its 
volume  of  the  gas,  and  that  the  solution  has  the  density  of  1-2109. 
According  to  Dr.  Thomson  one  cubic  inch  of  water,  at  the  tempera- 
ture of  G93  F.  is  capable  of  absorbing  417*8*22  cubic  inches  of  muriatic 
acid  gas,  and  when  cooled  down  to  the  temperature  of  the  air,  occu- 
pies the  space  of  1*3433  cubic  inch.  One  cubic  inch  of  this  acid  con- 
tains 31  1-041  cubic  inches  of  muriatic  acid  gas,  and  it  has  a  density  of 
1-1958  and  contains  40-39  per  cent,  of  real  acid,  united  with  50-61  of 
water.  In  winter  he  has  obtained  muriatic  acid  of  as  high  a  specific 
gravity  as  1-212. 

Dr.  Thomson  has  constructed  a  table  which  exhibits  the  specific 
gravit}r  of  this  acid  of  determinate  strength.  His  method  of  proceed- 
ing was  to  saturate  a  given  weight  of  the  acid  with  calcarious  spar. 
Every  50  grains  of  spar,  (or  pure  marble,)  dissolved,  indicated  the 
presence  of  37  grains  of  muriatic  acid.  Knowing  the  exact  strength 
of  one  particular  acid,  it  was  easy,  by  the  addition  of  determinate 
weights  of  water,  to  form  acid  of  any  inferior  strength  required. — 
Thomson's  First  Princip.  i.  88,  87. 

Directions  for  obtaining  liquid  muriatic  acid  are  given  in  most  of  the 
Pharmacopeias.  The  process  recommended  by  the  Edinburgh  college 
is  very  good.  The  proportions  they  prescribe  are  equal  weights  of 
common  salt,  water  and  sulphuric  acid,  more  acid  being  purposely  em- 
ployed than  is  sufficient  to  forma  neutral  sulphate  with  the  soda,  so 
that  the  more  perfect  decomposition  of  the  salt  may  be  insured.  To 
prevent  too  violent  an  action  at  first,  the  acid  is  mixed  with  one  third 
its  weight  of  water,  and  when  the  mixture  is  cool,  it  is  thrown  into 
the  vessel  containing  the  salt.  The  heat  of  a  sand  bath  or  lamp  is 
now  applied  and  the  distillation  is  continued  to  dryness.  The  gas  that 
is  formed  passes  into  a  receiver,  which  is  luted  to  the  retort,  arid  con- 
tains about  twice  the  quantity  of  water  used  in  diluting  the  sulphuric 
acid.  By  this  process  muriatic  acid  may  be  obtained  of  the  specific 
gravity  of  1-170. 

Liquid  muriatic  acid  has  the  following  properties  : 

1.  It  emits  white  suffocating  fumes,  consisting  of  muriatic  acid  gas, 
which  becomes  visible  by  contact  with  the  moisture  of  the  air. 

2.  When  heated  in  a  retort  or  glass  bottle,  muriatic  acid  gas  is  dis- 
engaged, and  may  be  collected  over  mercury. 

3.  Liquid  muriatic  acid  is  not  decomposed  by  the  contact  of  char- 
coal, essential  oils,  or  other  combustible  bodies. 

4.  When  diluted  with  water,   an  elevation  of  temperature  is  pro- 
duced, much  less  remarkable,  however,  than  that  occasioned  by  dilut- 
ing sulphuric  acid;  and  when  the  mixture  has  cooled  to  its  former 
temperature,  a  diminution  of  volume  is  found  to  have  ensued. 

5.  In  a  perfectly  pure  state,  liquid  muriatic  acid  is  quite  colourless  ; 
but  it  has  frequently  a  yellowish  hue.     This  may  proceed  either  from 
a  portion  of  chlorine  or  muriate  of  iron,  but  most  commonly  of  the 
latter.     This  colour  is  instantly  destroyed  by  a  few  drops  of  muriate 


120  HYDROGEN. 

of  tin  ;  but  this  addition,  instead  of  diminishing,  obviously  increases 
the  impurity  of  the  acid. 

USES.  Muriatic  acid  is  used  in  large  quantities  in  the  preparation  of 
muriate  of  tin.  It  is  also  used  in  several  other  arts,  and  is  a  valuable 
re-agent  in  the  laboratory. 

Views  concerning  the  nature  of  Muriatic  Acid. — The  theoretical  views 
concerning  the  nature  of  muriatic  acid,  have  undergone  many  and 
important  changes.  Scheele  considered  it  a  compound  of  a  certain 
base  and  an  imaginary  principle,  called  phlogiston.  It  was  afterwards 
supposed  to  be  a  simple  body,  which,  by  its  union  with  oxygen,  form- 
ed oxymuriatic  acid,  now  called  chlorine.  And  this  opinion  prevailed 
until  the  experiments  of  Sir  H.  Davy,  Gay  Lussac  and  Thenard  left  no 
doubt  that  chlorine  is  an  undecompounded  substance,  and  that  muriat- 
ic acid  is  a  compound  of  chlorine  and  hydrogen.  For  the  discussions 
on  this  subject  the  reader  may  consult  the  works  and  papers  referred 
to  under  the  article  chlorine,  page  102. 

REFERENCES.  Gay  Lussac  and  Thenard's  Recherches,  Phys.  Chim.  v  2, 
Davy's  Elements  of  Chem.  On  the  quantity  of  real  Acid  in  Liquid  Hydro- 
chloric, by  Dr.  Ure,  Ann.  of  Phil.  x.  268.  The  chapter  on  Muriatic  Acid, 
in  ChaptaPs  Chem.  iii.  83.  Far  the  methods  of  Manufacture,  fyc.  see  Cray's 
Operative  Chemist,  426. 

HYDROGEN    AND    IODINE. 

Hydriodic  Acid — Jltom.  Num.   127 — Symb.  I-f  H — Sp.  gr. 
4-1092  air=l. 

This  acid  was  discovered  by  Gay  Lussac,  and  to  him  and  Davy  we 
are  indebted  for  a  knowledge  of  most  of  its  properties. 

PROPERTIES.  A  colourless,  transparent  gas,  of  an  acid  taste  and  an 
odour  similar  to  that  of  muriatic  acid  ;  reddens  litmus  powerfully  ; 
does  not  support  combustion  ;  is  partly  decomposed  by  a  red  heat, 
and  completely  when  mixed  with  oxygen,  forming  water  and  separat- 
ing the  iodine  ;  forms  white  fumes  when  admitted  into  the  air,  and  is 
rapidly  absorbed  by  water,  resembling,  in  both  these  respects,  muriatic 
acid;  when  brought  into  contact  with  chlorine  it  is  decomposed,  mu- 
riatic acid  being  formed,  and  the  vessel  is  filled  with  the  vapour  of 
iodine  ;  it  is  also  decomposed  by  many  of  the  metals,  as  potassium, 
sodium,  zinc,  iron,  mercury,  &c.  at  ordinary  temperatures,  the  iodine 
combining  with  the  metal,  and  the  hydrogen  passing  off. 

NATIVE  STATE.  Hydriodic  acid  is  found  native  in  several  species  of 
Fucus,  in  sponges,  &c.  usually  in  combination  with  potassa  or  soda. 
Vauquelin  has  also  detected  it  in  combination  with  silver. 

PREPARATION.     This  gas  may  be  procured, 

1.  By  passing  a  mixture  of  hydrogen  gas  and  the  vapour  of  iodine 
through  a  red  hot  porcelain  tube. 

2.  It  may  also  be  obtained  quite  pure  by  the  action  of  water  on  the 
iodide  of  phosphorus.     For  this  purpose  we  introduce  into  a  small  re- 
tort some  moistened  iodine,    and  afterwards   add  to  it  one-eighth  or 
one-twelfth  its  weight  of  phosphorus.     An  iodide   of  phosphorus  is 
formed,  which  instantly  reacts  upon  the  water.     Mutual  decomposition 


HYDROGEN.  121 

ensues  ;  the  oxygen  of  the  water  unites  with  the  phosphorus,  and  the 
hydrogen  with  the  iodine,  giving  rise  to  the  formation  of  phosphoric 
and  hydriodic  acids.  On  the  application  of  a  moderate  heat  the  latter 
passes  over  in  the  form  of  a  colourless  gas,  and  is  collected  in  receiv- 
ers, filled  with  common  air,  which,  by  a  proper  management,  it  will 
expel  by  its  superior  specific  gravity. 

Liquid  Hydriodic  Acid,  or  the  solution  of  hydriodic  acid  in  water, 
is  fuming,  and  when  saturated  has  a  density  of  1  -7.  It  does  not  act 
upon  mercury,  although  in  the  gaseous  state  it  attacks  it  powerfully. 
Chlorine  takes  the  hydrogen  from  this  compound;  muriatic  acid  is 
formed  and  iodine  is  liberated.  It  is  slowly  decomposed  by  contact 
with  air,  the  hydrogen  being  attracted  by  the  oxygen  of  the  atmos- 
phere ;  it  is  also  decomposed  by  galvanic  electricity,  by  concentrated 
sulphuric  and  nitric  acids,  and  by  those  oxides  which  hold  their  oxy- 
gen loosely.  With  other  oxides  it  combines  and  forms  a  genus  of 
neutral  salts,  called  Hydriodates. 


HYDROGEN    AND    BROMINE. 

Hydrobromic  Acid— Atom.  Num.  79'26 — Symb.  Br+H. 

Discovered  by  M.  Balard. 

PROPERTIES.  A  colourless  gas,  with  an  intensely  acid  taste ;  by 
contact  with  atmospheric  air  gives  white  vapours,  more  dense  than  those 
produced  by  hydrochloric  acid,  under  the  same  circumstances  ;  it 
has  a  pungent  irritating  odour ;  is  decomposed  by  chlorine,  which 
instantly  liberates  abundant  vapours,  that  condense  into  drops  of  bro- 
mine ;  decomposed  at  common  temperatures  by  potassium,  in  which 
case  a  volume  of  hydrogen  remains,  exactly  equivalent  to  half  that  of 
the  original  gas.  And  hence  its  composition  is  analogous  to  that  of 
hydriodic  and  hydrochloric  acids,  being  equal  volumes  of  bromine  and 
hydrogen  without  condensation.  The  salts  of  this  acid  are  termed 
Hydrobro  mates. 

Hydrobromic  acid  is  very  soluble  in  water,  which,  by  absorbing  the 
gas,  increases  in  volume,  acquires  great  density,  and  also  the  property 
of  emitting  white  vapours  by  contact  with  the  air.  This  solution  is 
colourless  and  possesses  the  principal  properties  of  the  gas. 

PREPARATION.  Hydrobromic  acid  is  generated  by  exposing  a  mix- 
ture of  hydrogen  and  bromine  to  the  flame  of  a  taper,  or  what  is  stil! 
better,  by  introducing  an  ignited  iron  rod  into  a  bottle  containing  it. 
It  may  also  be  procured  by  a  process  analogous  to  that  used  for  hydri- 
odic acid  gas.  Bromine  and  phosphorus,  placed  in  contact,  and  mois- 
tened with  a  few  drops  of  water,  afford  abundantly  a  gas  which  is  the 
acid  in  question. 

HYDROGEN    AND    FLUORINE. 

Hydrofluoric  Acid — Atom.  Num.  19-68 — Symb.  F+H. 

The  property  which  Fluor  or  Derbyshire  Spar  possesses  of  corroding 
glass  when  mixed  with  sulphuric  acid,  is  said  to  have  been  known  at 
Nuremberg  as  early  as  1670.  Scheele,  in  1771,  pointed  out  that  the 
property  of  corroding  glass  was  due  to  an  acid  given  off  by  the  action 


122  HYDROGEN. 

of  sulphuric  acid  upon  fluor  spar.    Gay  Lussac  and  Thenard,  however, 
first  pointed  out  the  method  of  obtaining  the  acid  in  a  pure  form. 

PROPERTIES.  Hydrofluoric  acid  at  the  temperature  of  32°  F.  is  a 
colourless  fluid,  remaining  in  that  state  at  59°  F.  if  preserved  in  well 
stopped  bottles  ;  but  when  exposed  to  the  air  flies  off  in  dense  white 
fumes,  which  consist  of  the  vapour  of  the  acid  in  combination  with 
the  moisture  of  the  air;  its  specific  gravity  when  first  prepared  is,  1*06, 
but  is  increased,  by  the  gradual  addition  of  water,  to  1-55,  and  there  is 
no  known  instance  of  a  similar  condensation ;  its  vapours  are  highly 
irritating,  and  when  applied  to  the  skin  it  disorganizes  it  so  rapidly 
as  to  occasion  dangerous  ulcers  ;  in  addition  to  the  usual  properties  of 
a  powerful  acid,  it  acts  strongly  on  glass  and  corrodes  it  deeply  ;  it 
also  dissolves  some  bodies  which  resist  the  action  even  of  nitro-muri- 
atic  acid,  as  silicium.  zirconium  and  columbium  ;  when  brought  into 
contact  with  potassium,  violent  detonation  takes  place,  hydrogen  gas 
escapes,  and  a  white  compound,  fluoride  of  potassium,  is  generated  ; 
with  the  alkalies  it  forms  salts,  called  Hydrofluates. 

Hydrofluoric  acid  corrodes  glass. — When  glass  is  brought  into  contact 
with  this  acid,  its  transparency  is  instantly  destroyed  This  effect  is 
produced  by  the  union  of  the  acid  with  the  silex  of  the  glass,  and  the 
product  is  a  colourless  gas  known  by  the  name  of  jluo-silicic  acid.  It 
is  in  consequence  of  this  affinity  for  siliceous  matter  that  plates  of 
glass,  covered  with  a  composition  of  beeswax  arid  turpentine,  and 
drawn  upon  with  a  graver,  may  have  those  parts  which  are  laid  bare 
etched  by  exposure  either  to  the  vapour  or  to  the  diluted  acid. 

PREPARATION.  As  glass  is  immediately  corroded  by  this  acid,  we 
must  employ  vessels  of  lead  or  silver  in  procuring  it.  The  following 
method  is  suggested  by  Gay  Lussac.  A  retort  of  pure  lead  must  be 
procured,  composed  of  two  pieces  which  slip  into  each  other.  To 
this  retort  must  be  adapted  a  leaden  receiver.  Take  any  quantity  of 
pure  fluor  spar,  reduce  it  to  a  fine  powder,  and  put  it  into  the  re- 
tort, then  mix  it  well  with  twice  its  weight  of  concentrated  sulphuric 
acid.  Lute  the  joining  of  the  retort  and  the  beak  where  it  enters  the 
receiver  with  clay,  then  apply  a  moderate  heat  to  the  retort,  taking 
care  that  it  is  not  so  great  as  to  fuse  the  lead.  The  receiver  is  to  be 
surrounded  with  a  mixture  of  common  salt  and  snow.  The  acid  is 
disengaged  and  collected  in  the  receiver  in  a  liquid  state. 

For  the  purpose  of  exhibiting  the  effects  of  the  vapour  upon  glass, 
a  small  square  or  oblong  leaden  vessel  will  suffice.  Into  this  the  fluor 
spar  and  sulphuric  acid  are  to  be  put  and  gentle  heat  afterwards  ap- 
plied. 

Attempts  have  been  made  to  effect  the  decomposition  of  this  acid, 
both  upon  the  supposition  that  it  may  be  a  compound  of  an  electro- 
positive body,  such  as  sulphur  with  oxygen,  or  that  it  is  constituted 
of  a  highly  electro  negative  element,  like  chlorine,  in  union  with  hy- 
drogen. The  latter  view  is,  of  the  two,  the  best  supported  by  experi- 
ment and  analogy.  A  strong  argument  in  its  favor  is  derived  from 
the  fact  discovered  by  Kuhlman,  that  fiuor  spar  is  not  decomposed  by 
the  anhydrous  sulphuric  acid.  [Ann.  de  Chim.  et  dc  Phys.  Feb.  1827.] 
There  being  no  water  to  furnish  oxygen  to  the  calcium,  or  hydrogen 
to  the  fluorine,  the  hydrofluoric  acid  cannot  be  produced. 

REFERENCES.  Puymaurin  on  the  action  of  Fluoric  Acid  on  silidons 
Earth,  and  engraving  with  it  on  Glass,  Repert.  of  Arts.  1st.  ser.  v.  210,  271. 
Gay  Lussac  and  Tlwiard  on  the  Fluoric  Acid,  and  Us  decomposition ',  Jour. 


NITROGEN.  123 

de  Phys.  Jan-wary,  18(K»,  and  Repert.  of  Arts,  <2d  ser.  xv.  90.  Davifs  ex 
periinents  on  Fluoric  Acid,  Phil.  Trans.  1812,  and  in  Reper.  of  Arts, 
^d  ser.  xxii.  72.  Berzelius  on  Fluoric  Acid  and  its  most  remarkable  com- 
binations, Ann,  of  Phil.  xxiy.  and  xxv. — Also,  Traite  de  Chirn.  by  the  same 
author. 


SECTION  II. 

NITROGEN. 
Atom.  Num.  U—Symb.  N—Sp.  gr.  0-9722  air=l. 

First  noticed  as  a  distinct  gas  by  Dr.  Rutherford,  in  1772.  But  first 
discovered  as  a  constituent  part  of  the  atmosphere  by  Lavoisier,  in 
1775,  who  named  it  Azote.  It  has  also  been  called  Mephitic  Air,  but 
Nitrogen  appears  to  be  the  most  appropriate  name. 

PROPERTIES.  A  gaseous  body  without  colour,  taste  or  odour  ;  does 
not  support  combustion  nor  animal  life  ;  is  not  inflammable  like  hy- 
drogen, though  under  favourable  circumstances  it  may  be  made  to 
unite  with  oxygen;  is  very  sparingly  absorbed  by  water. 

It  extinguishes  burning  bodies. — This  can  be  easily  shown  by  im- 
mersing a  lighted  taper  or  candle  into  a  vessel  of  nitrogen  gas. 

Does  not  support  animal  life. — Although  no  animal  can  live  in  an 
atmosphere  of  nitrogen,  yet  it  exerts  no  injurious  action  either  on  the 
lungs  or  on  the  system  at  large,  the  privation  of  oxygen  being  the  sole 
cause  of  death.  Indeed  this  gas  is  more  distinguished  by  negative 
characters  than  any  striking  quality. 

NATIVE  STATE.  Nitrogen  gas  is  sometimes  given  off  by  hot  springs. 
Dr.  Daubeny  has  found  it  in  hot  springs  in  Scotland,  on  the  Alps  and 
in  France. 

PREPARATION.     Nitrogen  gas  may  be  obtained  in  several  ways. 

1.  By  burning  a  piece  of  phosphorus  in  a  jar  of  air  inverted  over 
water.     The  strong  affinity   of  phosphorus  for  oxygen,  enables  it  to 
burn  till  the  whole  of  that  gas  is  consumed.     The  product  of  the 
combustion,  pyrophosphoric  acid,  is  at  first  diffused  through  the  resi- 
due in  the  form  of  a  white  cloud  ;  but  is  rapidly  absorbed  by  water,  and 
disappears  in  the  course  of  half  an  hour.     The  residual  gas  is  nitro- 
gen, containing  a  small  quantity  of  carbonic  acid  and  vapour  of  phos- 
phorus, both  of  which  may  be  removed  by  agitating  it  briskly  with  a 
solution  of  pure  potassa.     This  process  is  usually  adopted. 

2.  By  introducing   a   solution  of  proto-sulphate   of  iron,    charged 
with  the  deutoxide  of  nitrogen,  into  a  vessel  of  atmospheric  air — the 
oxygen  will  be  absorbed  in  a  few  minutes.     A  stick  of  phosphorus 
produces  the  same  effect  in  24  hours,  if  exposed  to  a  temperature  of 
60°  F.     A  solution  of  the  sulphuret  of  potassa  or  of  lime — or  a  paste 
made  of  equal  parts  of  iron  filings  and  sulphur,  with  water,  acts  in  a 
similar  manner. 

3.  By  exposing  a  mixture  of  fresh  muscle  and  nitric  acid  of  spe- 
cific  gravity  1*20    to  a  moderate   temperature,    effervescence   takes 
place  and  nitrogen  is  liberated,  mixed  however,  with  carbonic  acid, 
which  may  be  separated  by  lime  water. 


124  NITROGEN. 

In 'all  these  processes,  except  the  last,  the  theory  of  which  is  some- 
what complex,  some  substance  is  brought  into  contact  with  atmos- 
pheric air  which  has  a  strong  affinity  for  its  oxygen,  with  which  it 
forms  a  compound  and  leaves  the  nitrogen  in  a  separate  state.  It 
should  be  remarked,  that  nitrogen  may  also  be  obtained  by  the  action 
of  chlorine  on  ammonia,  in  a  manner  to  be  explained  when  treating 
of  that  alkali. 

USES.  Nitrogen  is  without  use  in  the  arts  or  in  medicine.  But  it 
must  perform  some  important  office  in  the  animal  economy,  since  the 
only  difference  between  animal  and  vegetable  substances  consists  in 
the  presence  or  absence  of  this  principle. 

NATURE  OF  NITROGEN.  Though  nitrogen  is  ranked  among  the 
simple  non-metallic  bodies,  Berzelius,  Davy  and  others  have  maintain- 
ed the  opinion  that  it  is  compound.  But  this  view  does  not  appear 
to  be  supported  by  experiment.  Those  who  are  desirous  of  examining 
the  facts  and  reasonings  in  favour  of  this  opinion,  are  referred  to  Ber- 
zelius' paper  on  the  nature  of  Azote,  &c.  in  Ann.  of  Phil.  ii.  276,  and 
to  the  2d  volume  of  his  Traite  de  Chim.  ii.  339  ;  to  Davy  in  Phil. 
Trans.  1810,  and  to  J.  Miers,  on  the  composition  of  Azote,  in  Ann. 
of  Phil.  iii.  364,  iv.  180,  260. 

REFERENCES.  Rutherford's  Dissertation  de  Acre  Mephitica.  Scheele  on 
Air  and  Fire.  Lavoisier's  Elements.  Priestley  on  Air.  For  particulars 
concerning  the  preparation  of  Nitrogen,  by  the  decomposition  of  Ammonia, 
see  Berzelius,  i.  240. 

Atmospheric  Air. 

Atmospheric  air  was  for  many  centuries  believed  to  be  an  elemen- 
tary body.  Although  many  philosophers  deserve  the  merit  of  having 
thrown  doubts  over  this  opinion,  its  true  nature  was  demonstrated 
about  the  same  time  by  Scheele  and  Lavoisier. 

PROPERTIES.  Atmospheric  air  is  a  gaseous  substance,  transparent, 
invisible,  without  odour  or  taste,  and  it  is  not  sensible  to  the  toucli 
unless  in  motion  ;  is  perfectly  elastic  and  compressible  ;  has  a  pressure 
at  the  level  of  the  sea,  equal  to  a  weight  of  about  15  pounds  on  every 
square  inch  of  surface,  and  can  support  a  column  of  water  34  feet  high 
and  a  column  of  mercury  of  30  inches  ;  has  a  density  of  1,000,  being 
the  standard  with  which  the  density  of  all  other  elastic  fluids  is1  com- 
pared ;  100  cubic  inches  of  it  in  a  pure  and  dry  state  weigh,  according 
to  the  recent  experiments  of  Proutand  others,  31  grains  at  60°  F.  and 
30  Bar.— Henry,  i.  320. 

The  chemical  properties  of  atmospheric  air,  are  owing  chiefly  to  the 
oxygen  which  it  contains,  the  presence  of  which  is  necessary  to  its 
salubrity  ;  it  is  a  bad  conductor  of  electricity,  for  when  this  fluid  has 
accumulated  on  the  surface  of  a  body,  and  passes  to  another  body 
through  the  air,  it  is  always  in  the  form  of  sparks  ;  it  is  not  changed 
by  high  degrees  of  heat  or  cold  ;  is  changed  with  few  exceptions  by 
the  simple  combustibles,  at  various  temperatures,  absorbing  its  oxygen 
and  liberating  its  nitrogen. 

I  shall  now  briefly  notice  some  of  the  most  important  of  the  above 
named  properties. 

Compressibility  and  Elasticity. — The  compressibility  of  air  is  shown 
by  the  fact  that  a  quantity  of  it  may  be  compressed  or  condensed,  into 


NITROGEiN.  125 

a  very  small  compass ;  as  is  exemplified  in  the  common  fire  syringe, 
and  in  the  air  gun.  In  these  cases,  of  course,  the  particles  of  which 
the  air  is  composed  are  brought  nearer  together  by  the  compression. 
The  elasticity  of  air  may  be  shown  by  putting  a  bladder  half  full  of 
air,  under  the  receiver  of  an  air  pump  and  exhausting.  As  we  with- 
draw the  air,  or  in  other  words  diminish  the  pressure,  the  bladder  be- 
comes distended  in  consequence  of  the  expansion  of  the  air  within  it. 
This  elasticity  is  a  force  of  considerable  energy  ;  for  when  air  is  high- 
ly compressed  its  effort  to  recover  its  proper  bulk  is  prodigious  ;  and 
so  great  that  it  will  sometimes  burst  the  strongest  vessels.  Hence  the 
well  known  danger  of  forcing  too  much  air  into  the  ball  of  an  air  gun  : 
it  bursts  and  occasions  great  mischief. 

The  extreme  compressibility  and  elasticity  of  the  air  accounts  for 
the  facility  with  which  it  is  set  in  motion,  and  the  velocity  with  which 
it  is  capable  of  moving.  It  is  subject  to  the  laws  which  characterize 
elastic  fluids  in  general.  It  presses,  therefore,  equally  on  every  side  ; 
and  when  some  parts  of  it  become  lighter  than  the  surrounding  por- 
tions, the  denser  particles  rush  rapidly  into  their  place  and  force  the 
more  rarefied  ones  to  ascend.  The  motion  of  air  gives  rise  to  various 
familiar  phenomena.  A  stream  or  current  of  air  is  wind,  and  an 
undulating  vibration  excites  the  sensation  of  sound. 

Weight  and  Pressure. — That  the  air  is  possessed  of  weight  was  first 
suspected  by  Galileo  in  1640,  and  afterwards  placed  beyond  doubt  by 
the  experiments  of  Torricelli  arid  Pascal,  in  1643.  Torricelli  ascer- 
tained that  when  a  glass  tube  of  about  three  feet  in  length  and  closed 
at  one  end,  was  filled  with  quicksilver  and  inverted  in  a  basin  of  the 
same  fluid,  the  mercury  fell  about  six  inches,  so  that  the  atmosphere 
appeared  capable  of  counterbalancing  a  column  of  mercury  of  about 
30  inches.  By  this  experiment  the  Barometer  was  in  fact  constructed  ; 
but  it  required  the  observation  of  Paschal  that  upon  ascending  a  moun- 
tain the  quicksilver  fell  in  the  tube,  because  there  was  less  air  above  to 
press  upon  the  surface  of  the  metal  in  the  basin, — to  prove  that  an 
instrument  of  great  value  had  thus  been  invented. 

The  pressure  of  the  air,  as  is  shown  by  the  barometer,  is  extremely 
variable.  It  varies  according  to  the  elevation  above  the  level  of  the 
sea,  and  on  this  principle  the  height  of  mountains  is  estimated.  It 
also  varies  at  the  same  place,  and  on  this  depends  the  indications  of 
the  barometer  as  a  weather-glass.  For  although  we  are  still  ignorant 
of  the  cause,  observation  has  fully  proved,  that  the  weather  is  com- 
monly fair  and  calm  when  the  barometer  is  high,  and  usually  wet  and 
stormy  when  the  mercury  falls. 

It  is  obvious  that  as  the  pressure  of  the  air  diminishes  as  we  ascend 
from  the  surface  of  the  earth,  the  greater  the  elevation,  the  lighter 
must  be  the  air.  But  it  is  not  exactly  known  to  what  height  the  at- 
mosphere extends.  From  calculations  founded  on  the  phenomena  of 
refraction,  its  height  is  supposed  to  be  about  45  miles  ;  and  Dr.  Wol- 
laston  estimates,  from  the  law  of  the  expansion  of  gases,  that  it  is  40 
miles.  How  far  it  extends  beyond  this  point  is  a  subject  for  specula- 
tion. Dr.  Wollaston,  from  astronomical  observations  made  by  himself 
and  Capt.  Kater,  infers  that  the  atmosphere  is  of  finite  extent.  On 
this  point  see  Wollaston  on  the  finite  extent  of  the  atmosphere. — PkiL 
Trans.  1822,  and  in  Ann.  of  Phil.  xx.  151. 

These  properties  of  the  air,  are  most  strikingly  illustrated  by  the 
Air  Pump,  an  instrument  which  in  its  construction  resembles  the  com- 
mon sucking  pump,  excepting  that  all  the  parts  are  more  accurately 
made,  the  object  being  to  exhaust  the  air  as  completely  and  as  expe- 

I 


126  NITROGEN. 

ditiously  as  possible.  If  the  receiver  be  placed  on  the  plate  of  the 
pump  and  exhausted,  we  are  unable  to  move  it,  because  it  is  kept  down 
by  the  weight  of  the  air  around  it.  Or  if  a  long  tube  with  a  stop-cock 
be  exhausted  by  the  pump,  and  then  have  the  cock  opened  under  water, 
the  fluid  will  be  forced  in  by  the  pressure  of  the  air  on  the  surface  of 
the  water  in  the  basin. 

Constitution  of  the  Air. — The  researches  of  Davy,  Dalton,  Gay  Lus- 
sac,  Thomson  and  others,  leave  no  doubt  that  pure  atmospheric  air 
consists  of  nearly  21  of  oxygen  and  79  nitrogen  in  the  100  volumes. 
But  the  atmosphere  is  never  absolutely  pure  ;  or  rather,  in  addition  to 
the  above  gases,  it  always  contains  a  variable  quantity  of  aqueous  va- 
pour and  carbonic  acid.  According  to  Vogel  and  others,  air  within  a 
certain  distance  from  the  sea,  contains  a  little  muriatic  acid.  [Ann.  of 
Phil.  xxii.  25,]  and  Liebig  states  that  a  trace  of  nitric  acid  is  discover- 
able in  rain  which  has  fallen  immediately  after  lightning.  [Henry's 
Chem.  i.  321.]  In  addition  to  these,  the  odoriferous  matter  of  flowers 
and  other  volatile  substances,  are  also  frequently  present  in  the  air. 

The  presence  of  watery  vapour  in  the  air,  may  be  shown  by  the  ex- 
periments noticed  under  water,  [p.  114  ]  The  amount  varies  accord- 
ing to  the  temperature,  and  these  variations  are  determined  by  the 
Hygrometer. 

The  presence  of  carbonic  acid  in  the  air  may  be  shown  by  exposing 
to  it  a  vessel  of  lime  water.  A  pellicle  soon  forms  on  the  surface  of 
the  solution,  which  by  agitation  sinks  to  the  bottom  and  is  soon  suc- 
ceeded by  another.  Upon  analysing  this  precipitate,  it  is  found  to  be 
carbonate  of  lime,  the  carbonic  acid  of  which  must  have  been  derived 
from  the  air  with  which  the  lime  water  was  surrounded.  But  the 
quantity  of  this  gas  in  the  air  is  quite  inconsiderable,  although  it  is 
liable  to  variation.  According  to  Mr.  Dalton  it  does  not  usually  ex- 
ceed 1  in  1000  parts  ;  and  T.  Saussure  has  recently  found  that  10,000 
parts  of  air  contain  4*9  of  carbonic  acid  as  a  mean,  6-2  as  a  maximum, 
and  3'7  as  a  minimum. 

The  knowledge  of  the  composition  of  the  air,  and  of  the  importance 
of  oxygen  to  the  life  of  animals,  naturally  gave  rise  to  the  notion  that 
the  healthiness  of  the  air,  at  different  times,  and  in  different  places, 
depends  on  the  relative  quantity  of  this  gas.  It  was,  therefore,  sup- 
posed that  the  purity  of  the  atmosphere,  or  its  fitness  for  communica- 
ting health  and  vigour,  might  be  discovered  by  determining  the  pro- 
portion of  oxygen  ;  and  hence  the  origin  of  the  term  Eudiometer,  which 
was  applied  to  the  apparatus  for  analyzing  the  air.  But  this  opinion, 
though  at  first  supported  by  the  discordant  results  of  the  earlier  anal- 
yses, was  soon  proved  to  be  fallacious.  It  appears,  on  the  contrary, 
that  the  composition  of  the  air  is  not  only  constant  in  the  same  place, 
but  is  the  same  in  all  regions  of  the  earth,  and  at  all  altitudes.  Air 
collected  at  the  summit  of  the  highest  mountains,  such  as  Mont-Blanc 
and  Chirnborazo,  contains  the  same  proportions  of  oxygen  as  that  of 
the  lowest  valleys.  The  air  of  Egypt  was  found  by  Berthollet  to  be 
similar  to  that  of  France.  The  air  which  Gay  Lussac  brought  from 
an  altitude  of  21,735  feet  above  the  earth,  had  the  same  composi- 
tion as  that  collected  at  a  short  distance  from  its  surface.*  Even  the 

*  Mr.  Faradav's  analysis  of  air  from  the  Arctic  regions,  shows  a  decided 
and  constant  difference  between  it  and  the  air  of  London,  of  at  least  1  374 
per  cent.  A  pp.  to  Parry's  3d  Voyage,  Lond.  ed.  p.  249.  This  difference  is 
supposed  by  Dr.  Torrey  to  bo  owing  to  a  deficiency  of  vegetation  in  high 
northern  latitudes. — Sillimarfs  Chemistry,  i.  19S. 


NITROGEN.  127 

miasmata  of  marshes,  and  the  effluvia  of  infected  places,  owe  their 
noxious  qualities  to  some  principle  of  too  subtile  a  nature  to  be  detect- 
ed by  chemical  means,  and  not  to  a  deficiency  of  oxygen*.  Seguin 
examined  the  infectious  atmosphere  of  an  hospital,  the  odour  of  which 
was  almost  intolerable,  and  could  discover  no  appreciable  deficiency  of 
oxygen,  or  other  peculiarity  of  composition. — Turner.  For  descrip- 
tions of  various  kinds  of  Eudiometers,  see  Webster's  Brande  and  Ure's 
Dictionary. 

Concerning  the  nature  of  the  union  which  exists  among  the  several 
elastic  fluids  constituting  the  atmosphere,  two  opposite  opinions  pre- 
vail. By  the  greater  part  of  chemists,  it  has  been  considered  as  a 
chemical  compound,  chiefly  from  the  uniformity  of  its  composition  and 
from  the  fact  that  its  several  ingredients  do  not  arrange  themselves  ac- 
cording to  their  respective  specific  gravities.  On  the  other  hand,  Mr. 
Dalton  has  advanced  the  theory  that,  of  the  various  elastic  fluids  con- 
stituting the  atmosphere,  the  particles  of  one  have  neither  attractive 
nor  repulsive  power  towards  those  of  another  ;  but  that  the  weight  or 
pressure  upon  any  one  particle  of  a  fluid  mixture  of  this  sort,  arises 
solely  from  the  particles  of  its  own  kind.  According  to  this  hypothe- 
sis, oxygen,  nitrogen  and  carbonic  acid  gases,  (or  indeed  any  number,) 
may  exist  together,  under  any  pressure,  and  at  any  temperature,  while 
each  of  them,  however  paradoxical  it  may  at  first  appear,  occupies  the 
space  allotted  for  all.  Each  ingredient  of  the  atmosphere,  on  this 
view,  exerts  its  own  separate  pressure  in  supporting  the  mercury  of  the 
barometer.  This  theory  appears  to  be  loaded  with  fewer  difficulties 
than  that  which  considers  the  constituents  of  the  atmosphere  to  be 
held  together  by  chemical  affinity. 

But  our  limits  will  not  permit  a  detail  of  the  arguments  in  its  sup- 
port. Mr.  Dalton  has  fully  explained  his  views  respecting  the  consti- 
tution of  the  atmosphere,  in  the  Phil.  Trans,  for  1826. 

On  this  subject  see  also  the  papers  of  Mr.  Graham  and  Dr.  Mitchell 
of  Philadelphia,  on  the  diffusion  of  the  Gases. — Journal  of  the  Roy. 
Ins.  ii.  101.  Jour,  of  Science,  N.  S.  vi.  74. 

REFERENCES.  Priestley  on  Airs.  Scheele's  Essay  on  Air  and  Fire.  La- 
voisier's  Elements  of  Chemistry.  Thenard's  Traite.  de  Chitn.  i  272.  Art- 
Aeronautics,  in  the  Supplement  to  the  Encyclopedia  Britannica,  containing 
an  account  of  the  Aerial  Ascent  of  M.  M.  Biot  and  Gay  Lussac,  and  of  their 
observations  upon  the  higher  Atmosphere,  t^c. 

NITROGEN    AND    OXYGEN. 

We  are  at  present  acquainted  with  five  definite  compounds  of  these 
substances,  the  composition  of  which,  as  determined  by  Gay  Lussac, 
Henry  and  Davy,  is  as  follows : 

By  volume.  By  iceight. 

Protoxide  of  nitrogen,    .       .       100  N.       50  O.         14  N.       8  O=22. 

*  An  interesting  fact  was  observed  by  Dr;  Prout,  while  engaged  in  an  ex- 
tensive series  of  experiments  on  the  weight  of  dry  atmospheric  air:  viz.  that 
during  the  existence  of  the  epidemic  cholera  in  London  in  1832,  the  air  uni- 
formly possessed  a  weight  above  the  usual  standard.  "  It  would  seem,"  gays 
he,  '*  as  if  some  heavy  foreign  bod\r  had  been  diffused  through  the  lower  re. 
gions  of  the  atmosphere  about  this  period,  and  which  was  somehow  or  other 
connected  with  the  disease  in  question." — Reports  of  the  Brit.  Association 
fo<-  1832. 


128  NITROGEN. 


Deutoxide  of  nitrogen,  . 
Hyponitrous  acid, 

.       100  N. 
.       100  N. 
100  N. 

100  O. 
150  O. 

200  O. 

14  N. 
14  N. 
14  N. 

16O=30. 
24  O=38. 
32  O=46. 

Nitric  acid, 

.       100  N. 

250  O. 

14  N. 

40  O=54. 

Protoxide  of  Nitrogen— Atom.  Num.  22 — Symb.  O-f-N — Sp. 
gr.  1-527  air=l. 

This  curious  substance  was  discovered  by  Priestley,  in  1772,  and  has 
been  examined  with  much  care  by  Berthollet,  Davy,  Gay  Lussac  and 
Thenard.  It  has  successively  received  the  names  of  Dephlogisticated 
Nitrous  Gas.  Nitrous  Oxide,  and  Gaseous  Oxide  of  Azote ;  but  the  ap- 
pellation above  given  is  in  strict  conformity  with  the  principles  of 
chemical  nomenclature. 

PROPERTIES.  A  colourless  gas,  without  odour,  and  of  a  slightly 
sweetish  taste  ;  does  not  affect  vegetable  blues,  even  when  mixed 
with  atmospheric  air  ;  supports  combustion,  most  substances  burning 
in  it  with  greater  energy  than  in  the  atmosphere  ;  it  is  respirable,  pro- 
ducing, when  breathed,  a  high  degree  of  excitement,  similar  to  that  of 
the  early  stages  of  intoxication  ;  but  when  animals  are  wholly  confin- 
ed in  it  they  die  very  speedily  ;  it  is  absorbed  by  water  at  60 J  F.  in  the 
proportion  of  three  fourths  of  its  volume,  and  hence  it  should  be  col- 
lected over  warm  water;  it  is  decomposed  by  heat  and  by  the  electric 
spark  ;  it  is  liquified  by  pressure.  It  also  possesses,  as  well  as  the 
deutoxide,  the  property  of  combining  with  the  pure  alkalies. 

It  supports  combustion. — The  glowing  wick  of  an  extinguished  taper 
or  candle,  when  introduced  into  a  vessel  of  this  gas,  is  immediately 
kindled  by  it  into  a  flame.  Iron  wire  and  red  hot  charcoal  burn  in  it, 
with  nearly  the  same  splendour  as  in  oxygen  gas,  but  for  a  shorter 
time.  Phosphorus  introduced  into  it,  in  a  state  of  active  inflamma- 
tion, burns  with  great  violence,  almost  approaching  to  explosion. 
When  mixed  with  hydrogen  it  will  detonate,  either  by  the  application 
of  flame  or  the  electric  spark. 

In  each  of  the  above  cases,  the  combustible  combines  with  oxygen, 
forming  water,  an  oxide,  or  an  acid,  and  nitrogen  is  set  at  liberty. 

It  is  respirable  when  mixed  with  atmospheric  air.— It  has  been  ob- 
served that  animals  wholly  confined  in  pure  protoxide  of  nitrogen 
speedily  die.  It  may,  however,  be  taken  into  the  lungs  without  be- 
ing fatal,  because  it  is  mixed  and  diluted  with  the  air  present  in  that 
organ  One  of  the  most  extraordinary  properties  of  this  gas,  first 
ascertained  by  the  bold  experiments  of  Davy,  in  1799,  is  that  it 
produces,  when  breathed,  a  transient  intoxication,  or  violent  exhil- 
aration. 

To  administer  the  gas,  it  may  be  introduced  into  an  oiled  silk  bag 
or  clean  bladder,  furnished  with  a  stop-cock,  and  it  may  be  breathed 
repeatedly  from  the  bag  and  back  again,  as  long  as  it  will  last. 
The  sensations  produced  are,  in  general  highly  pleasurable  and  re- 
semble those  attendant  on  the  early  period  of  intoxication.  Great 
exhilaration,  an  irresistible  propensity  to  laughter,  a  rapid  flow  of  vivid 
ideas,  and  an  unusual  fitness  for  muscular  exertion,  are  the  ordinary 
feelings  it  produces.  But  the  effects  of  the  gas  are  different  upon 
persons  of  different  temperaments  and  constitutions.  Some  interest- 
ing notices  of  its  operation  upon  distinguished  men  in  England,  are 


NITROGEN.  129 

to  be  found  in  lire's  Chemical  Dictionary.  In  general  these  feelings  of 
exhilaration  are  not  followed  by  any  thing  more  than  a  slight  sensa- 
tion of  languor,  probably  from  the  effects  of  muscular  exertion  alone; 
but  it  should  not  be  concealed  that  its  administration  is  occasionally 
attended  with  unpleasant  consequences,  and  should,  upon  the  whole, 
be  rather  discouraged  than  recommended.  Two  cases  of  this  sort  are 
related  by  Professor  Silliman,  as  having  occurred  at  New-Haven. — 
Amer.  Jour.  v.  194. 
PREPARATION.  The  protoxide  of  nitrogen  may  be  obtained, 

1.  By  exposing  deutoxide  of  nitrogen  for  a  few  days  to  iron  filings, 
or  to  various  other  bodies  strongly  attracting  oxygen,  the  former  gas 
is  changed  into  the  protoxide,  one  half  of  its  oxygen  combining  with 
the  metal. 

2.  By  the  decomposition  of  the  nitrate  of  ammonia,  a  salt  obtained 
by  the  action  of  pure  nitric  acid  upon  the  carbonate  of  ammonia,  and 
subsequent  evaporation.     When  this  salt  is  put  into  a  glass  retort  and 
exposed  to  the  temperature  of  between  4  and  500°,  it  liquifies,  bub- 
bles of  gas  begin  to  rise  from  it,  and  in  a  short  time  a  brisk  efferves- 
cence ensues,   which  continues   till  the  whole  of  the  salt  disappears. 
The  heat  should   be  cautiously  regulated  to  avoid  explosion,  which 
takes  place  when  the  temperature  reaches  that  of  a  red  heat.     The  gas 
should  be  collected  over  warm  water  and  allowed  to  stand  a  short  time 
before  it  is  used. 

The  above  process  may  be  easily  explained. 

Nitrate  of  ammonia  consists  of 

Nitric  acid, 1  atom=54 

Ammonia, 1  atom =17 

71 

Nitric  acid  consists  of  Ammonia  consists  of 

Nitrogen,     -     -     1    atom  =14        Nitrogen,     -     -     -     -    1   atom=14 
Oxygen,       -     •    5  atoms  =40         Hydrogen,  ....  3  atoms  =  3 

54  17 

Now  by  the  application  of  heat  to  the  salt  the  hydrogen  combines 
with  so  much  oxygen  as  is  sufficient  for  forming  water,  and  the  re- 
maining oxygen  converts  the  nitrogen  both  of  the  nitric  acid  and  of 
the  ammonia  into  protoxide  of  nitrogen.  The  decomposition  of  the 
71  grains  of  salt  will  therefore  yield, 

Water, 3  atoms  =27 

Protoxide  of  nitrogen,          -  2  atorns=44 

71 

REFERENCES.  Davy's  Elements  of  Chem.  Phil.  Gay  Lussac  and  The- 
nard — Phys.  Chem.  Researches.  Faraday  on  impurities  in  Nitrous  Oxide. 
Branded  Jour.  vi.  360. 

Deutoxide  of  Nitrogen — Atom.  Num.  3Q—Symb.  2O-J-N — 
8p.gr.  l-041air=l. 

SYN.     Nitrous  Gas. — Nitric  Oxide. — Binoxide  of  Nitrogen. 

The  discovery  of  this  substance  is  due  to  Hales  j  but  its  properties 
were  first  investigated  by  Priestley. 


130  NITROGEN. 

PROPERTIES.  A  colourless  gas,  without  action  upon  litmus ;  is 
sparingly  absorbed  by  water ;  extinguishes  most  burning  bodies,  but 
charcoal  and  phosphorus,  if  immersed  in  it  when  in  a  state  of  vivid 
combustion,  burn  with  increased  brilliancy  ;  is  quite  irrespirable,  ex- 
citing a  strong  spasm  of  the  glottis,  as  soon  as  an  attempt  is  made  to 
inhale  it ;  is  decomposed  by  heat  and  electricity  ;  when  mixed  with 
oxygen  gas  assumes  an  orange  red  colour,  owing  to  its  combination 
with  an  additional  quantity  of  oxygen — the  same  thing  takes  place 
when  this  gas  comes  in  contact  with  atmospheric  air,  affording  a  con- 
venient test  of  its  presence  ;  when  mixed  with  hydrogen  it  burns  with 
a  green  flame,  but  does  not  explode  by  the  electric  spark. 

•fiction  of  Oxygen  Gas. — When  deutoxide  of  nitrogen  is  mixed  with 
oxygen  gas,  atmospheric  air  or  any  gaseous  mixture  that  contains 
oxygen  in  an  uncombined  state,  dense  suffocating  vapours,  of  an 
orange  red  colour,  are  produced,  called  nitrous  acid  vapours,  which  are 
copiously  absorbed  by  water,  and  communicate  acidity  to  it.  This 
effect  can  be  shown  by  the  following  experiment. 

Exp.  Paste  a  sheet  of  litmus  paper  within  a  glass  jar  ;  near  the  bot- 
tom, and  into  the  jar,  filled  with  and  inverted  in  water,  admit  so 
much  nitrous  gas,  previously  well  washed,  as  will  displace  the  water 
below  the  level  of  the  paper.  The  colour  of  the  litmus  will  remain 
unchanged ;  but  on  admitting  oxygen  gas  it  will  be  immediately  red- 
dened. 

It  is  from  this  property  of  absorbing  oxygen,  but  no  other  gas,  that 
nitrous  gas  has  been  applied  to  the  purpose  of  Eudiometry ,  or  of  as- 
certaining the  purity  of  atmospheric  air,  which  was  formerly  sup- 
posed to  depend  upon  a  varying  proportion  of  that  gas.  The  sources 
of  error,  in  its  employment  in  this  mode,  have  hitherto  been  consider- 
ed such  as  to  forbid  our  relying  implicitly  on  the  results  which  it  may 
afford.  But  Dalton  and  Gay  Lussac  maintain  that  it  may  neverthe- 
less be  employed  in  eudiometry  ;  and  have  described  the  precautions 
which  are  required  to  ensure  accuracy.  Mr.  Dalton  has  given  his 
process  in  the  10th  volume  of  the  Annals  of  Philosophy  ;  and  further 
directions  have  been  published  by  Dr.  Henry,  in  his  Elements.  The 
method  of  Gay  Lussac,  which  is  preferred  by  Dr.  Turner,  may  be 
found  in  the  2d  volume,  p.  247,  Mernoires  d'  Arcucil. 

PREPARATION.  The  deutoxide  of  nitrogen  may  be  easily  obtain- 
ed by.  pouring  upon  filings  or  turnings  of  copper,  put  into  a  retort  or 
gas  bottle,  some  nitric  acid,  diluted  with  twice  its  bulk  of  water ;  an 
action  ensues,  red  fumes  are  produced,  and  there  is  a  copious  evolu- 
tion of  the  gas  which  may  be  collected  over  water.  The  first  por- 
tions should  be  rejected,  as  containing  nitrogen  and  nitrous  acid  gases. 
The  deutoxide  of  nitrogen  is  presently  recognized,  by  the  red  fumes 
which  it  produces  when  brought  into  contact  with  air.  During  this 
process  a  portion  of  the  nitric  acid  is  decomposed  ;  part  of  its  oxy- 
gen uniting  with  the  copper,  converts  it  into  the  peroxide  of  copper  ; 
while  another  part  is  retained  by  the  nitrogen  of  the  nitric  acid,  form- 
ing the  deutoxide  of  nitrogen.  The  peroxide  of  copper  attaches  itself 
to  some  undecomposed  nitric  acid,  and  forms  the  blue  nitrate  of  cop- 
per. Many  other  metals  are  oxidized  by  nitric  acid,  with  the  disen- 
gagement of  a  similar  compound  ;  but  none,  mercury  excepted,  yields 
BO  pure  a  gas  as  copper. 

REFERENCES.  Davy's  Elements  of  Chem.  Phil.  Gay  Lussac — Mem. 
d'Arcueily'n. 


NITROGEN.  131 

Hyponitrous  Acid — Atom.  Num.  38 — Symb.  30-J-N. 

From  the  experiments  of  Gay  Lussac,  it  appears  that  there  ex- 
ists an  acid  formed  of  100  measures  of  nitrogen  and  150  of  oxygen. 
When  he  passed  into  a  glass  tube  confined  over  mercury  500  or  600 
parts  of  deutoxide  of  nitrogen,  100  parts  of  oxygen,  with  some  solu- 
tion of  pure  potassa,  there  was  uniformly  an  absorption  of  500  parts, 
consisting  of  the  100  oxygen  and  400  deutoxide  of  nitrogen.  These 
Ibrmed  an  acid  which  combined  with  the  potash.  JSow  as  400  mea- 
sures of  deutoxide  of  nitrogen  consist  of  200  oxygen  and  200  nitro- 
gen^ it  follows  that  the  acid  must  be  composed  of  200  measures  ni- 
trogen and  300  oxygen,  or  100  and  150,  as  above  stated.  It  con- 
tains therefore,  three  times  more  oxygen  tlian  the  protoxide  of  ni- 
trogen. 

This  acid  is  also  produced,  according  to  Gay  Lussac,  by  keeping  the 
deutoxide  of  nitrogen  for  three  months  in  a  glass  tube,  in  contact 
with  a  concentrated  solution  of  potassa.  At  the  end  of  this  time  100 
parts  of  the  deutoxide  are  reduced  to  25  parts  of  the  protoxide  of  ni- 
trogen, and  crystals  of  hyponitrite  ofpotash  are  also  formed. — The- 
nard,  ii.  193. 

Hyponitrous  acid  has  not  yet  been  obtained  in  a  separate  state. 
When  we  attempt  to  separate  it  from  potassa  by  means  of  an  acid,  it 
is  converted  into  deutoxide  of  nitrogen,  which  is  disengaged,  and  ni- 
trous or  nitric  acid  which  remain  in  solution.  Berzelius  does  not 
recognize  the  hyponitrous  as  a  distinct  acid — and  thinks  it  ought 
not  to  be  admitted  as  such  in  the  nomenclature. — Traite.  de  CJiim. 
II  41, 

Nitrous  Acid— Atom.  Num.  48— Symb.  40+N. 

This  acid  appears  to  have  been  known  for  some  time,  but  was  con- 
founded with  nitric  acid,  being  known  under  the  name  of  Fuming 
Nitrous  Acid.  Its  true  nature  has  been  made  known  by  Davy,  Gay 
Lussac  and  Dulong. 

PROPERTIES.     Nitrous  acid  exists  in  a  gaseous  and  liquid  state. 

The  gaseous  acid  is  characterized  by  its  orange  red  colour  ;  is  quite 
irrespirable,  exciting  great  irritation  and  spasm  of  the  glottis,  even 
when  moderately  diluted  with  air  ;  supports  the  combustion  of  burn- 
ing phosphorus  and  of  a  lighted  taper,  but  extinguishes  burning  sul- 
phur. 

The  liquid  anhydrous  acid  is  powerfully  corrosive,  has  a  strong  acid 
taste,  and  pungent  odour  ;  is  of  a  yellowish  orange  colour  at  the  ordin- 
ary pressure  and  temperature,  but  at  low  temperatures  becomes  colour- 
less ;  has  a  density  of  1-451  ;  preserves  the  liquid  form  at  the  ordinary 
temperature  and  pressure,  and  boils  at  82J  F. ;  evaporates  with  great 
rapidity  when  exposed  to  the  atmosphere,  forming  common  nitrous 
acid  vapours,  which  when  once  mixed  with  air,  or  other  gases,  require 
intense  cold  to  condense  them. 

PREPARATION.  This  acid  never  exists  in  nature.  The  gaseous  acid 
may  be  formed  by  mixing  oxygen  gas  with  the  deutoxide  of  nitrogen. 
The  operation,  however,  must  not  be  conducted  over  water  or  mercury. 
The  presence  of  the  former  determines  the  production  of  nitric  acid  ; 
the  latter  is  oxidized  by  the  nitrous  acid,  and  therefore  decomposes  it 
Sir  H.  Davy  made  this  compound  by  mixing  two  measures  of  the 


132  NITROGEN. 

deutoxide  of  nitrogen,  and  one  of  oxygen,  free  from  moisture,  in  a  dry 
glass  vessel,  previously  exhausted  by  an  air  pump.  Nitrous  acid  va- 
pours were  produced,  and  a  contraction  ensued,  amounting  to  about 
one  half  the  volume  of  the  mixed  gases. 

The  liquid  anhydrous  acid  may  be  obtained  by  a  more  easy  process 
than  the  above.  For  this  purpose  dry  and  neutral  nitrate  of  lead  is 
to  be  exposed  to  heat  in  a  glass  retort.  The  nitric  acid  of  the  salt  is 
in  this  manner  resolved  into  nitrous  acid  and  oxygen  ;  and  if  the  pro- 
ducts are  received  in  vessels  kept  moderately  cool,  the  greater  part  of 
the  former  condenses  into  a  liquid. 

REFERENCES.  Davy's  Elements  of  Chem.  Phil.  Dulong,  in  Ann.  de 
Chim.  et  de  Ph.  ii.  317.  R.  Philips  and  Dr.  Hope^s  controversy  concern- 
ing its  preparation,  Ann.  of  Phil.  xvii.  59, 189.  xviii.  24. 

Nitric  Acid— Atom.  Num.  54—Symb.  50+N—  Sp.gr.  1-510 
\vater=l. 

SYW.     Spirits  of  Nitre.     Aqua  Fortis. 

This  acid  is  said  to  have  been  discovered  about  1225,  by  Ramond 
Lully,  in  distilling  a  mixture  of  nitrate  of  potassa  and  clay  ;  but  its 
nature  was  not  well  understood  until  1785,  when  it  was  examined  by 
Cavendish.  Since  that  time,  its  properties  have  been  investigated  by 
Davy,  Dalton  and  Gay  Lussac. 

PROPERTIES.  Nitric  acid,  in  its  highest  state  of  concentration,  is 
liquid,  odorous,  white  and  very  corrosive ;  destroys  the  skin  and 
changes  it  to  a  yellow  colour  ;  is  eminently  poisonous  ;  possesses  acid 
properties  in  a  high  degree,  a  single  drop  of  it,  though  largely  diluted 
with  water,  reddening  litmus  permanently  ;  in  its  most  pure  and 
concentrated  state  has  the  specific  gravity  of  1-50  or  1-510,  con- 
taining still  in  this  state  a  considerable  quantity  of  water,  from 
which  it  cannot  be  separated  without  decomposition  or  by  uniting 
with  some  other  body  ;  boils  at  248°  F.  and  may  be  distilled  with- 
out change ;  is  frozen  by  cold,  the  temperature  at  which  congela- 
tion takes  place  varying  with  the  strength  of  the  acid,  the  strongest 
freezing  at  50°  below  zero  ;  it  is  decomposed  by  solar  light  and  by 
several  of  the  combustibles  ;  forms  with  bases,  salts  which  are  called 
Nitrates. 

It  is  decomposed  by  solar  light. — When  very  concentrated,  liquid  ni- 
tric acid  becomes  coloured  by  exposure  to  the  sun's  light,  passing  first 
to  a  straw  colour,  and  then  to  a  deep  orange.  This  effect  is  produced 
by  the  union  of  the  light  of  the  sun  with  oxygen,  in  consequence  of 
which  the  proportion  of  that  principle  to  the  nitrogen  is  diminished. — 
Henry,  i.  353. 

By  exposing  it  to  the  sun's  rays  in  a  gas  bottle,  the  bent  tube  of 
which  terminates  under  water,  oxygen  gas  may  be  procured. 

It  is  decomposed  by  various  combustible  bodies. — As  this  acid  retains 
its  oxygen  with  but  little  force,  it  is  decomposed  by  all  combustibles, 
which  are  oxygenized  by  it,  with  more  or  less  rapidity,  in  proportion 
to  their  affinity  for  oxygen. 

1.  When  brought  into  contact  with  hydrogen  gas  at  a  high  tempe- 
rature, by  transmitting  them  together  through  an  ignited  porcelain 
tube,  a  violent  detonation  ensues.  This  experiment,  therefore,  re- 


NITROGEN.  133 

quires  great  caution.  Dr.  Priestley  found  also  that  hydrogen  gas,  af- 
ter being  used  to  displace  nitric  acid  from  a  bottle  inverted  in  that 
liquid,  had  become  explosive. 

2.  Poured  on  perfectly  dry  and  powdered  charcoal,  it  excites  the 
combustion  of  the  charcoal,  which  becomes  red  hot,  and  emits  an  im- 
mense quantity  of  fumes. 

3.  It  also  inflames  essential  oils,  (as  those  of  turpentine  and  cloves) 
when  suddenly  poured  on  them.     In  these  experiments,  the  acid  should 
be  poured  out  of  a  bottle,  tied  to  the  end  of  a  long  stick  ;  otherwise 
the  operator's  face  and  eyes  may  be  severely  injured. 

4.  Nitric  acid  is  decomposed  by  boiling  it  in  contact  with  sulphur, 
which  attracts  the  oxygen  and  forms  sulphuric  acid. 

5.  This  acid  is  also  decomposed  by  metals  ;  as  iron,  tin,  copper,  &c. 
with  various  phenomena,  according  to  the  affinity  of  each  metal  for 
oxygen.     This  may  be  seen  by  pouring  some  strong  nitric  acid  on  iron 
filings  or  powdered  tin.     Violent  heat,  attended  with  red  fumes,  will 
be  produced,  and  the  metals  will  be  oxidized.  —Henry. 

PREPARATION.     This  may  be  effected  in  the  following  ways  : 

1.  The  direct  combination  of  nitrogen  and  oxygen,   affording  a  de- 
cisive synthetic  proof  of  the  nature   of  this  acid,  may  be  effected  by 
passing  electric   sparks  through  a  mixture  of  nitrogen   and  oxygen 
gases.     The  experiment  is  an  extremely  laborious  one,  and  requires  for 
its  performance,  a  powerful  electrical  machine. — See  Cavendish,  Phil. 
Trans.  Ixxv.     Hennjs  Chem.  i.  346. 

2.  This  acid  may  be  readily  produced  by  passing  the  deutoxide  of 
nitrogen  very  slowly  into  oxygen  gas,   standing  over  water.     By  this 
operation  four  volumes  of  the  former  combine  with  three  of  the  lat- 
ter, and  the  compound,  therefore,  must  consist  of  two  volumes  nitro- 
gen and  five  volumes  oxygen,  or  by  weight  of  one  proportion  of  nitro- 
gen and  five  proportions  of  oxygen. 

This  view  is  confirmed  by  the  experiments  of  Davy — by  the  analy- 
sis of  nitrate  of  baryta,  by  Dr.  Henry,  and  by  the  analysis  of  various 
nitrates,  by  Dr.  Thomson.  This,  however,  is  only  as  it  exists  in  the 
dry  state,  when  in  combination. 

3.  The  liquid  nitric  acid  of  commerce  is  abundantly  obtained  from 
the  decomposition  of  the  nitrates  by  means  of  sulphuric  acid  ;  and 
common  nitre  or  nitrate  of  potassa  being  the  cheapest,   is  always  se- 
lected for  this  purpose.     This  salt  previously  well  dried,  is  put  into 
a  glass  retort,  and  a  quantity  of  the  strongest  sulphuric  acid  is  poured 
upon  it.     On  applying  heat,  ebullition  ensues,  owing  to  the  escape  of 
nitrous  acid  vapours,  which  must  be  collected  in  a  receiver  kept  cold 
by  moist  cloths.     The  heat  should  be  steadily  increased  during  the  ope- 
ration, and  continued  as  long  as  any  acid  vapours  come  over. 

There  is  some  difference  among  chemists  as  to  the  best  proportions 
for  forming  nitric  acid.  The  London  college  recommends  equal 
weights  of  nitre  and  sulphuric  acid  ;  the  Edinburgh  and  Dublin  col- 
leges employ  three  parts  of  nitre  to  two  of  the  acid.  According  to 
Thomson,  when  61-8  parts  of  the  strongest  sulphuric  acid  of  com- 
merce are  mixed  with  12  3-4  parts  of  nitre  thoroughly  freed  from  wa- 
ter and  perfectly  pure,  the  acid  which  comes  over  is  the  strongest  that 
can  be  procured,  having  a  specific  gravity  of  1-55,  and  consists  of  one 
atom  of  acid  and  one  atom  of  water.  When  12  1-4  parts  of  sulphu- 
ric acid  are  mixed  with  12  3-4  parts  of  pure  anhydrous  nitre,  the  whole 


134  NITROGEN. 

nitric  acid  may  be  obtained  without  loss ;  but  its  specific  gravity  is 
only  1'4855,  and  it  is  a  compound  of  one  atom  real  acid  and  two  atoms 
water. — First  Princip.  i.  113. 

Thenard  states  that  1800  parts  of  well  dried  nitre  and  1800  parts  of 
sulphuric  acid  of  commerce,  yield  1020  parts  of  acid  of  equal  strength 
with  that  obtained  from  a  larger  proportion  of  sulphuric  acid,  and  he, 
therefore,  prefers  these  proportions. 

In  the  large  way,  and  for  purposes  of  the  arts,  it  is  usual  to  sub- 
stitute earthen  or  cast  iron  retorts,  made  extremely  thick,  for  those  of 
glass.  An  earthen  head  is  adopted,  and  this  is  connected  with  a  range 
of  proper  condensers.  The  strength  of  the  product  is  varied  also  by 
putting  more  or  less  water  into  the  receiver. 

IMPURITIES. — The  nitric  acid  of  commerce  is  seldom  perfectly  pure. 
It  may  contain  both  sulphuric  and  muriatic  acids  ;  the  former  being 
derived  from  the  acid  which  is  used  in  the  process  :  the  latter  from 
the  muriate  of  soda  which  is  sometimes  mixed  with  the  nitre.  These 
impurities  can  be  detected  by  adding  a  few  drops  of  a  solution  of  muri- 
ate of  baryta  and  nitrate  of  silver  to  separate  portions  of  nitric  acid, 
diluted  with  three  or  four  parts  of  distilled  water.  If  the  solution  of 
muriate  of  baryta  cause  a  cloudiness  or  precipitate,  sulphuric  acid 
must  be  present ;  if  a  similar  effect  be  produced  by  nitrate  of  silver, 
the  presence  of  muriatic  acid  may  be  inferred.  Nitric  acid  is  purified 
from  sulphuric  acid  by  re-distilling  it  from  a  small  quantity  of  the  ni- 
trate of  potassa,  with  the  alkali  of  which,  the  sulphuric  acid  unites 
and  remains  in  the  retort.  To  separate  muriatic  acid,  it  is  necessary 
to  drop  a  solution  of  nitrate  of  silver  into  nitric  acid  as  long  as  a  pre- 
cipitate forms,  and  draw  off  the  pure  acid  by  distillation.  It  should  be 
kept  in  well  stopped  glass  bottles,  and  in  a  dark  place,  as  the  light  ef- 
fects its  decomposition. 

TESTS  OF  NITRIC  ACID.  Liebig,  some  time  since,  proposed  the  blue 
colour  of  the  sulphate  of  indigo  as  a  test  for  the  presence  of  nitric  acid, 
but  this  substance  is  decolourized  by  so  many  agents  that  no  reliance 
can  be  placed  in  its  indications.  A  very  delicate  and  apparently  un- 
objectionable test,  is  the  orange  red  followed  by  a  yellow  colour,  which 
nitric  acid  communicates  to  morphine.  The  supposed  nitrate  is  heated 
in  a  test  tube  with  a  drop  of  sulphuric  acid  and  then  a  crystal  of  mor- 
phine is  added.  For  this  fact  we  are  indebted  to  Dr.  O'Shaugnessy. — 
Lancet  1829—30. 

ACTION  ON  THE  ANIMAL  ECONOMY. — This  substance  is  of  course  highly 
poisonous,  when  taken  internally  in  its  concentrated  form,  causing 
death  speedily,  though  never  suddenly.  In  these  cases  neutralizing 
agents  should  be  administered  as  soon  as  possible,  to  prevent  the  action 
of  the  poison.  —  See  Beck's  MedicalJuris.  3d  ed.  489. 

USES. — Nitric  acid  is  of  considerable  use  in  the  arts.  It  is  employ- 
ed for  etching  on  copper,  as  a  solvent  of  tin  to  form  with  that  metal  a 
mordant  for  some  of  the  finest  dyes  ;  in  metallurgy  and  assaying  ;  in 
various  chemical  processes,  on  account  of  the  facility  with  which  it 
parts  with  oxygen  and  dissolves  metals  ;  in  medicine  as  a  tonic,  &c. 
For  the  purposes  of  the  arts  it  is  co<nmonly  used  in  a  diluted  state  and 
much  contaminated  with  the  sulphuric  and  muriatic  acids,  under  the 
name  of  Aqua  Fortit.  This  is  generally  prepared  by  mixing  common 
nitre  with  an  equal  weight  of  sulphate  of  iron,  and  half  its  weight  of 
the  same  sulphate  calcined,  and  distilling  the  mixture  ;  or  by  mixing 
the  nitre  with  twice  its  weight  of  dry  powdered  clay  and  distilling  in  a 


NITROGEN.  135 

reverberatory  furnace.  Two  kinds  are  found  in  the  shops,  one  called 
double  aquafortis,  which  is  about  half  the  strength  of  nitric  acid  ;  the 
other  simply  aqua  fortis,  which  is  half  the  strength  of  the  double. — 
Ure's  Chem.  Diet. 

REFERENCES.  Davy's  Elements  of  Chem.  Phil.  Daltorfs  New  System 
of  Chem.  Gay  Lussac's  Mem.  d'Arcueilj  ii.  and  Ann.  de  Chim.  tt  de  Phys. 
i.  394.  Thenardj  Traite  de  Chim.  ii.  169.  Dr.  Ure  and  R.  Phillips1  con- 
troversy concerning  the  constitution  of  Liquid  Nitric  Acid. — Brande's  Jour. 
ir.  291,  v.  163,  vi.  242,  vii.  171.  Chaptafs  Account  of,  and  its  Manufacture. 
Chem.  applied  to  the  Arts,  iii.  49,  to  78.  On  the  same  subject,  see  Aikin's 
Diet,  of  Chem.  and  Gray's  Operative  Chemist. 

Nitro- Muriatic  Acid. 

This  term  has  been  applied  to  the  Aqua  Regia  of  the  alchemists — 
an  acid,  which  may  be  formed  by  mixing  two  parts  by  weight  of  nearly 
colourless  nitric  with  one  of  liquid  muriatic  acid.  Proust  employs 
only  one  of  nitric  to  four  of  muriatic  acid.  The  mixture  evolves 
chlorine,  a  paitial  decomposition  of  both  acids  having  taken  place, 
and  water,  chlorine  and  nitrous  acid  gas,  are  thus  produced ;  that  is, 
the  hydrogen  of  the  muriatic  acid  abstracts  oxygen  from  the  nitric  to 
form  water  :  the  result  must  be  chlorine  and  nitrous  acid. — Davy  in 
Brande's  Jour.  i.  67. 

For  every  101  parts  in  weight  of  real  nitric  acid,  [equivalent  to  118 
hydro-nitric  acid,]  which  are  decomposed,  67  parts  of  chlorine,  ac- 
cording to  Sir  H.  Davy,  are  produced.  Upon  this  view  it  is  not  cor- 
rect to  say  that  aqua  regia  oxidates  gold  or  platinum,  since  it  merely 
causes  their  combination  with  chlorine.  By  long  continued  and  gen- 
tle heat,  nitro-muriatic  acid  may  be  entirely  deprived  of  chlorine,  and 
it  then  loses  its  power  of  acting  on  gold  or  platinum.— Henry,  i.  355. 
*vThe  nitro-muriatic  acid  does  not  form,  with  alkaline  or  other  bases, 
a  distinct  genus  of  salts,  entitled  to  the  name  of  nitro-muriates  ;  for, 
when  combined  with  an  alkali  or  an  earth,  the  solution  yields,  on  eva- 
poration, a  mixture  of  a  muriate  and  a  nitrate ;  and  metallic  bodies 
dissolved  in  it  yield  muriates  only. — Henry,  i.  355. 

The  most  remarkable  property  of  nitro-muriatic  acid  is  that  of  dis- 
solving gold  and  platinum. 

NITROGEN    AND    CHLORINE. 

Chloride  of  Nitrogen — Atom.  Num.  155-8 — Symb.  4C1+N — 
Sp.gr.  1-653  water=l. 

An  extraordinary  compound,  discovered  by  Dulong,  in  1811 — and 
which  has  been  subsequently  examined  by  Sir  H.  Davy  and  others. 

PROPERTIES.  An  oily  liquid,  of  a  yellow  colour,  and  an  irritating 
and  peculiar  odour,  analogous  to  that  of  chloro- carbonic  acid  ;  does 
not  congeal  by  the  intense  cold  produced  by  a  mixture  of  snow  and 
salt ;  may  be  distilled  at  160°  F.  without  change  j  at  212°  F.  explodes, 
and  is  decomposed  into  chlorine  and  nitrogen  ;  explodes  also  upon 
the  contact  of  phosphorus  and  many  of  the  oils  at  common  tempe- 
ratures ;  vaporizes  rapidly  when  in  contact  with  air,  emitting  a  suffo- 
cating odour. 


136  NITROGEN. 

Explodes  upon  the  contact  of  certain  combustibles. — Chloride  of  nitro- 
gen is  one  of  the  most  explosive  substances  yet  known,  and  it  was  the 
cause  of  serious  accidents  both  to  the  discoverer  and  to  Sir  H.  Davy. 
Great  caution  is  therefore  necessary  in  its  preparation  and  exhibition. 
From  the  experiments  of  Messrs.  Porrett,  Wilson  and  Kirk,  it  appears 
that  it  may  be  exploded  by  the  mere  contact  of  certain  combustibles, 
as  phosphorus,  and  the  fixed  and  volatile  oils.  Olive  oil  in  one  of  the 
best  for  exhibiting  the  nature  of  the  chloride,  as  it  seldom,  if  ever  fails 
to  produce  an  explosion. — Nicholson's  Jour,  xxxiv. 

PREPARATION.  Chlorine  and  nitrogen  have  but  a  slight  affinity  for 
each  other  ;  they  do  not  combine  at  all  when  presented  to  each  other 
in  the  gaseous  form,  and  when  combined  separate  with  great  facility. 
The  chloride  of  nitrogen  can  only  be  formed  by  presenting  chlorine  to 
nascent  nitrogen.  For  this  purpose  some  salt  of  ammonia  is  employ- 
ed. Its  formation  is  owing  to  the  decomposition  of  the  ammonia, 
(being  a  compound  of  hydrogen  and  nitrogen)  the  hydrogen  combines 
with  a  portion  of  the  chlorine  and  forms  muriatic  acid,  while  the  ni- 
trogen combines  with  another  portion  of  the  chlorine  and  gives  rise  to 
the  chloride  of  nitrogen. 

The  simplest  mode  of  obtaining  this  compound  consists  in  filling  a 
perfectly  clean  glass  basin  with  a  solution  of  about  one  part  of  sal- 
ammoniac  in  twelve  of  water,  and  inverting  into  it  a  tall  jar  of  chlo- 
rine. The  saline  solution  is  gradually  absorbed  and  rises  into  the  jar, 
a  film  forms  on  its  surface,  and  acquires  a  deep-yellow  colour ;  at 
length  small  globules,  looking  like  yellow  oil,  collect  upon  its  surface,  . 
and  successively  fall  into  the  liquid  beneath.  The  drops  of  chloride 
of  nitrogen,  as  they  descend,  should  be  collected  in  a  small  saucer  of 
lead,  placed  for  that  purpose  under  the  mouth  of  the  bottle.  In  this 
they  may  be  exploded  by  a  long  rod  with  the  extremity  dipped  in  oil. 

REFERENCES.  Davy  in.  Phil.  Trans.  1813,  and  notices  of  the  same  in 
Ann.  of  Phil.  \.  63,  71.  ii.  150.  Notice  of  Dulong's  Experiments,  Ann.  of 
Phil.  iv.  306. 

NITROGEN    AND    IODINE. 

Iodide  of  Nitrogen— Atom.  Num.  392—Symb.  3I+N. 

Discovered  by  M.  Courtois. 

PROPERTIES.  A  dark  coloured  powder,  which  explodes  spontane- 
ously when  dry,  and  with  a  slight  degree  of  heat  when  moist ;  emits 
heat  and  light  during  the  explosion,  and  iodine  and  nitrogen  are  set 
free  ;  is  readily  decomposed  by  the  alkalies. 

From  the  experiments  of  M.  Colin,  as  well  as  from  theoretical  con- 
siderations, Gay  Lussac  believes  that  it  consists  of  three  atoms  of 
iodine  and  one  atom  of  nitrogen. — [Ann.  de  Chim.  xci.  262.]  But  all 
attempts  to  collect  the  products  of  its  detonation  with  accuracy,  have 
failed.  [Colin' s  paper  on  some  combinations  of  iodine,  is  copied  from 
the  Jour,  de  Phys.  into  the  Repertory  of  Arts,  2d  ser.  xxvi.] 

PREPARATION.  Iodine  and  nitrogen  cannot  be  made  to  combine  di- 
rectly, but  combination  takes  placa  when  the  nitrogen,  in  a  nascent 
state,  is  brought  into  contact  with  iodine.  This  compound  may  be  ob- 
tained by  putting  iodine  into  a  solution  of  ammonia  at  ordinary  tem- 
peratures. A  portion  of  the  ammonia  is  soon  decomposed,  and  there 
result  an  iodide  of  nitrogen  which  falls  down  in  the  form  of  a  black- 


NITROGEN.  137 

ish  precipitate,  and  a  hydriodate  of  ammonia  which  remains  in  solu- 
tion. At  the  expiration  of  half  an  hour,  the  powder  may  be  thrown 
upon  a  filter  and  washed,  but  the  washings  should  not  be  carried  too 
far,  otherwise  there  is  danger  of  its  spontaneous  decomposition  and 
explosion  while  on  the  filter. 

This  compound  may  also  be  obtained  by  adding  chloriodic  acid  to  a 
solution  of  ammonia. 


NITROGEX   A^D    HYDHOGEN. 

Ammonia-—  Atom.  Num.  l7.—  Symb.  3  H+N.  Sp.  gr.  0-5967 
air=l. 

Known  to  the  alchemists,  though  not  in  its  purity,  under  the  names 
of  Hartshorn,  Volatile  Alkali,  Spirit  of  Sal-ammoniac,  #c.  Dr.  Black 
first  pointed  out  the  difference  between  pure  ammonia  and  the  car- 
bonate. Dr.  Priestley  first  obtained  it  in  its  purest  form,  that  of  a  gas, 
which  he  termed  Alkaline  Air. 

PROPERTIES.  Ammonia  in  its  pure  state  is  a  gaseous  substance, 
without  colour,  of  a  strong  and  pungent  odour,  acting  powerfully  on 
the  eyes  and  nose  ;  is  quite  irrespirable,  but  when  diluted  with  air, 
may  be  taken  into  the  lungs  with  safety;  extinguishes  burning  bodies 
and  is  not  inflamed  by  their  approach,  but  is  however  in  a  low  de- 
gree inflammable,  the  flame  of  a  candle  being  somewhat  enlarged 
when  immersed  in  it,  and  tinged  of  a  yellow  colour,  at  the  moment  of 
its  being  extinguished  ;  becomes  a  transparent  colourless  liquid  at  the 
temperature  of  50°  F.  and  under  a  pressure  equal  to  6-5  atmospheres, 
also  according  to  Guy  ton  Morveau,  under  the  common  pressure,  by 
a  cold  of  70°  below  the  zero  of  Fahrenheit,  but  it  is  doubted  whether 
this  last  was  not  a  solution  of  ammonia  in  water  ;  possesses  alkaline 
properties  in  a  very  marked  degree,  changing  the  blue  of  litmus  to 
green,  and  the  yellow  of  turmeric  to  brown  ;  is  decomposed  when 
subjected  in  small  quantities  to  the  action  of  electricity  ;  has  a  pow- 
erful affinity  for  water,  and  must  therefore  be  collected  over  mercury. 

It  is  inflammable.  —  Ammoniacal  gas  is  not  sufficiently  inflammable 
to  burn  when  in  contact  with  common  air.  But  when  expelled  from 
the  extremity  of  a  pipe  having  a  small  aperture  surrounded  by  oxy- 
gen gas,  it  may  be  kindled,  and  it  then  burns  with  a  pale  yellow  flame, 
the  products  of  its  combustion  being  water  and  nitrogen  gas.  —  Henry, 
i.  426. 

It  is  partly  decomposed  by  chlorine  and  iodine.  —  When  chlorine  gas 
is  mixed  with  pure  ammonia,  a  sheet  of  white  flame  pervades  the  mix- 
ture ;  part  of  the  ammonia  is  decomposed,  the  chlorine  is  converted 
into  muriatic  acid,  which  uniting  with  the  undecomposed  ammonia  is 
deposited  in  the  form  of  muriate. 

Exp.  The  simplest  way  of  showing  the  effect  produced  by  mixing 
these  two  gases,  is  to  invert  a  matrass  with  a  conical  neck  and  wide 
mouth,  over  another  with  a  taper  neck,  containing  a  mixture  of  mu- 
riate of  ammonia  and  lime,  heated  by  a  lamp.  As  soon  as  the  upper 
vessel  seems  to  be  full  of  ammonia,  by  the  overflow  of  the  pungent 
gas,  it  is  to  be  cautiously  lifted  up,  and  inserted  in  a  perpendicular 
direction,  into  a  wide  mouthed  glass  decanter  or  flask,  filled  with  chlo- 
rine. On  seizing  the  two  vessels  thus  joined,  with  the  two  hands 


138  NITROGEN. 

covered  with  gloves,  and  suddenly  inverting  them  like  a  sand  glass, 
the  heavy  chlorine  and  light  ammonia,  rushing  in  opposite  directions, 
unite  with  the  evolution  of  flame. — Ures  Chem.  Diet. 

When  we  employ  liquid  ammonia  and  gaseous  chlorine,  the  de- 
composition will  be  more  or  less  rapid,  and  will  cause  the  disen- 
gagement of  light  or  not,  according  as  the  contact  is  more  or  less  in- 
timate If  the  chlorine  is  disengaged  from  a  retort  and  passed  by 
means  of  a  tube  through  a  flask  filled  with  liquid  ammonia,  the  de- 
composition will  be  instantaneous  and  will  be  attended  with  the  dis- 
engagement of  light :  but  if  we  fill  a  flask  with  chlorine  and  plunge 
the  neck  into  liquid  ammonia  without  assisting  the  action  by  agita- 
tion, the  decomposition  will  be  less  rapid,  and  will  be  attended  only 
with  the  evolution  of  heat.—  [Thenard,  ii.  428.]  In  these  cases  the 
chlorine  combines  with  the  hydrogen  of  the  ammonia,  and  the  mu- 
riatic acid  thus  formed,  unites  with  an  undecomposed  portion  of  the 
ammonia  and  forms  the  muriate  of  that  alkali.  At  the  same  time 
also,  nitrogen  is  liberated  in  the  gaseous  form,  and  may  be  collected 
in  receivers  in  the  ordinary  way.  In  this  process  the  ammonia  should 
always  be  in  excess,  otherwise  it  is  wholly  converted  into  muriate  of 
ammonia,  and  the  nitrogen  combines  with  the  chlorine  and  forms  the 
highly  detonating  compound  already  described. — Berzelius,  i.  240. 

Ammonia  and  iodine  also  unite,  according  to  M.  Colin,  at  ordinary 
temperatures,  provided  both  are  perfectly  dry.  By  their  simple  con- 
tact a  viscid  liquid  is  formed,  which,  when  brought  into  contact  with 
water,  gives  rise  to  a  black  compound,  (iodide  of  nitrogen,)  which 
fulminates  when  slightly  compressed. — Ann.  de  Chim.  xci.  261. 

Ammoniacal  gas  may  be  decomposed  by  transmitting  it  through  a 
red  hot  porcelain  tube,  which  should  be  either  well  glazed  internally, 
or  covered  externally  with  a  lute.  It  has  been  ascertained  by  The- 
nard, that  when  any  of  the  five  following  metals  are  enclosed  in  the 
tube,  they  promote  the  decomposition  of  ammonia  at  a  temperature 
much  below  that  which  it  would  require  per  se,  in  the  order  set  down, 
viz.  iron,  copper,  silver,  gold  and  platinum  ;  iron  being  the  most  ef- 
fectual and  platinum  the  least.  Iron,  after  the  process,  is  found  to 
be  rendered  brittle,  and  copper  still  more  so.  The  gas  obtained  al- 
ways consists  of  three  parts  of  hydrogen  by  measure  and  one  of  nitro- 
gen. None  of  the  metals  either  increased  or  diminished  in  weight, 
and  they  can  only  therefore  act  as  conductors  of  heat.  Yet  it  is 
singular,  that  iron  decomposes  a  much  larger  quantity  than  platinum 
and  at  a  lower  temperature. — Henry,  i.  427.  Thenard,  ii.  433. 

M.  Savart,  who  has  recently  repeated  these  experiments  with  muck 
care,  finds  that  both  copper  and  iron  are  increased  slightly  in  weight, 
and  have  their  properties  somewhat  changed.  He  conceives  these 
facts  to  support  the  opinion,  that  nitrogen  is  the  oxide  of  a  base  call- 
ed provisionally  Ammonium,  which,  by  alloying  with  the  copper  and 
other  metals,  causes  the  change  in  their  properties. — \_Ann.  de  Chim. 
et  de  Phys.  xxxvii.  and  Brande's  Jour.  JV.  <S>.  iii.  476.]  These  results 
are  also  confirmed  by  the  experiments  of  Despretz. — Brande's  Jour.  J\\ 
8.  vii.  201. 

Ammoniacal  gas  is  absorbed  by  water. — A  drop  or  two  of  water  be- 
ing admitted  to  a  jar  full  of  this  gas,  confined  over  mercury,  the  gas 
will  be  immediately  absorbed,  and  the  mercury  will  rise  so  as  to  fill 
the  whole  of  the  jar,  provided  the  gas  be  sufficiently  pure.  Ice  pro- 
duces the  same  effect  in  a  still  more  remarkable  manner.  Water  by- 
saturation  with  this  gas,  acquires  its  peculiar  smell,  ar,d  constitutes 


NITROGEN.  139 

what  has  been  called  liquid  ammonia,  but  which  is  more  properly  a 
solution  of  pure  ammonia  in  water. 

Alcohol  also  absorbs  several  times  its  bulk,  and  affords  a  solution 
of  ammonia  which  possesses  the  strong  smell  and  other  properties  of 
the  gas.  This  is  commonly  called  Spirits  of  Hartshorn. 

Composition. — The  composition  of  ammonia  has  occupied  much  of 
the  attention  of  chemists.  Hydrogen  and  nitrogen  gases  do  not  unite 
directly,  and  therefore  we  have  no  direct  synthetic  proof  of  the  con- 
stitution of  ammonia.  But  it  is  produced  synthetically  during  the 
decomposition  of  many  animal  substances  ;  it  is  also  formed  during 
the  violent  action  of  nitric  acid  upon  some  of  the  metals,  and  by 
moistened  iron  filings  exposed  to  an  atmosphere  of  nitrogen.  In  these 
cases  the  nascent  gases  unite,  so  as  to  form  a  portion  of  ammonia. 

But  the  composition  of  ammonia  has  been  determined  analytically 
with  the  greatest  exactness.  When  a  succession  of  electric  sparks  is 
passed  through  ammoniacal  gas,  it  is  resolved  into  its  elements  ;  and 
the  same  effect  is  produced  by  conducting  ammonia  through  porce- 
lain tubes,  heated  to  redness.  The  late  A.  Berthollet  analyzed  am- 
monia in  both  ways,  and  ascertained  that  200  measures  of  that  gas, 
on  being  decomposed,  occupy  the  space  of  400  measures,  300  of  which 
are  hydrogen  and  100  nitrogen.  Dr.  Henry  has  recently  made  an  an- 
alysis of  ammonia  by  means  of  electricity,  and  his  experiment  proves 
beyond  a  doubt  that  the  proportions  above  given  are  rigidly  exact. — 
Ann.  of  Phil.  xxiv.  346. 

PREPARATION.  Ammonia  may  be  obtained  in  the  form  of  gas  in 
either  of  the  following  ways  : 

1.  Mix  together  equal  parts  of  muriate  or  sulphate  of  ammonia  and 
dry  quick-lime,  each  separately  powdered,   and  introduce  them  into  a 
small  gas  bottle  or  retort.     Apply  the  heat  of  a  lamp,  and  receive  the 
gas  that  is  liberated,  over  mercury. 

2.  To  a  saturated  solution  of  ammonia  in  water,  or  the  pure  liquid 
ammonia  in  a  gas  bottle,  apply  the  heat  of  a  lamp  ;  and  collect  the 
gas  as  in  the  former  case. 

Ammonia  has  heretofore  been  found  native  only  in  combination, 
1 .  with  muriatic  and  phosphoric  acids  in  the  urine  ;  2.  with  sulphuric 
acid  in  some  mines  of  alum ;  3.  with  carbonic  and  acetic  acid,  &c.  in 
putrid  animal  matter,  and  in  the  urine  of  all  animals. 

Solution  of  Ammonia  in  water. — This  is  commonly  but  incorrectly 
known  by  the  name  of  liquid  ammonia.  The  following  process  is 
given  by  Mr.  R.  Phillips,  as  preferable  to  that  of  the  London  Phar- 
macopeia.— Remarks  on  the  Lond.  Pharm.  34. 

On  nine  ounces  of  well-burnt  lime,  pour  half  a  pint  of  pure  water, 
and  when  it  has  remained  in  a  well  closed  vessel  about  an  hour,  add 
twelve  ounces  of  muriate  of  ammonia  (sal-ammoniac)  in  powder,  and 
three  pints  and  a  half  of  boiling  water.  When  the  mixture  has  cool- 
ed, pour  off  the  clear  portion,  and  distil  from  a  retort  twenty  fluid 
ounces.  The  specific  gravity  of  this  solution  is  0'954.  A  process  of 
Sig.  Bizio  is  described,  by  which,  from  every  pound  of  muriate  of  am- 
monia, 1  -Gl  of  a  pound  of  liquid  ammonia  may  be  obtained  of  specific 
gravity  0-910.  See  Brande's  Jour.  N.  S.  iii.  477. 

The  concentrated  solution  of  ammonia  as  thus  procured  is  a  clear 
colourless  liquid,  possessing  the  peculiar  pungent  odour,  taste,  alka- 
linity and  other  properties  of  the  gas  itself.  On  account  of  its  great 
volatility,  it  should  be  preserved  in  well  stopped  bottles,  a  measure 


140  NITROGEN. 

which  is  also  required  to  prevent  the  absorption  of  carbonic  acid. — 
At  the  temperature  of  130°  F.  it  enters  into  ebullition,  owing  to  the 
rapid  escape  of  pure  ammonia ;  but  the  whole  of  the  ga,s  cannot  be 
expelled  by  this  means,  as  at  last  the  solution  itself  evaporates.  It 
freezes  at  about  the  same  temperature  as  mercury. 

Tables  are  given  by  Sir  H.  Davy  and  Dalton,  showing  the  quantity 
of  real  ammonia  contained  in  100  parts  of  solutions  of  different  den- 
sities.— Elements  of  Ch&m.  Phil.  Henry,  i.  429. 

TESTS.  The  presence  of  ammonia  may  always  be  detected  by  its 
odour,  by  its  temporary  action  on  the  yellow  of  turmeric,  and  by 
forming  dense  white  fumes,  the  muriate  of  ammonia,  when  a  glas  rod 
moistened  with  muriatic  acid  is  brought  near  it.  Hydrated  oxide  of 
lead  is  also  a  test  of  ammonia. 

ACTION  ON  THE  ANIMAL  ECONOMY.  Cases  are  mentioned  where  the 
solution  of  ammonia  caused  death  in  the  space  of  a  few  minutes,  and 
in  a  late  work,  Orfila  adds  a  caution  against  its  too  free  use  with  per- 
sons who  have  fainted.  If  inspired  too  long,  the  vapour  inflames 
the  throat  and  lungs,  and  destroys  the  individual. — Beck's  Ned.  Juris. 
498. 

REFERENCES.  For  a  very  elaborate  account  of  Ammonia,  and  its  action 
on  various  substances,  see  Thtnard,  Trait,  de  Chim.  ii.  418.  Derzelius  on  the 
nature  of  Ammonia,  Ann.  of  Phil.  ii.  276,  and  Trait,  de.  Chim.  ii.  320. 
Dalton,  Ann  of  Phil.  ix.  186,  on  the  same  subject.  Pfaff  on  the  most  sensi- 
ble reagent  of  Ammonia,  Repert.  of  Arts.  2c/  ser.  xii.  66.  Phillips  and 
Hopt?s  controversy  on  the  preparation  of  solution  of  Ammonia,  Ann.  of 
Phil,  xv ii.  30,  xviii.  I'dl.  Faraday  on  the  combination  of  Chlorides  icith 
Ammonia,  Branded  Jour.  v.  7-1. 

SALTS    OP    AMMONIA    AND    THE    FOREGOING    ACIDS. 

The  salts  of  ammonia  are  generally  colourless  and  solid  at  com- 
mon temperatures,  except  the  subtiuoborate,  which  is  a  liquid.  They 
are  mostly  neutral ;  of  an  acrid  taste ;  those  with  an  excess  of  base 
having  an  amrnoniacal  odour.  A  few  of  them  are  acid  ;  almost  all 
crystallizable  ;  when  exposed  to  heat  are  either  wholly  or  in  part 
volatilized,  depending  upon  the  nature  of  the  acid  whether  gaseous  or 
fixed.  They  are  decomposed  by  chlorine  at  common  temperatures, 
and  when  mixed  with  potassa,  soda,  lithia,  baryta,  strontia  or  lime, 
ammonia  is  evolved. 

REFERENCES.  Dr.  Urt*s  experimental  researches  on  the  Ammoniacal 
Salts,  Ann.  of  Plul.  x.  203,  278. 

Chlorate  of  Ammonia. — Crystallizes  in  fine  needles  ;  of  a  very  sharp 
taste  ;  detonates  when  thrown  upon  hot  coals,  and  when  submitted  to 
a  gentle  heat  in  a  retort,  is  rapidly  decomposed  and  is  converted  into 
water,  chlorine,  nitrogen,  protoxide  of  nitrogen,  and  an  acid  hydro- 
chlorate  of  ammonia. 

This  salt  is  not  found  in  nature.  It  may  be  readily  obtained  by 
adding  carbonate  of  ammonia  to  chloric  acid  to  complete  saturation, 
and  then  evaporating  the  liquor.  The  evaporation  should  be  very 
carefully  conducted ;  indeed  it  should  be  in  a  manner  spontaneous,  to 
prevent  the  volatilization  of  the  salt.  It  is  of  no  use  in  the  arts. 

REFERENCES.  VauqueliiSs  description  of  Chi  or.  of  Am.  Arm.  de  Chim. 
xcv.  96.  Ann.  of  Phil.  vii.  39. 

**; 


NITROGEN.  141 

lodate  of  Ammonia. — Forms  small  indeterminate  crystals  ;  when 
heated  is  decomposed  into  oxygen,  nitrogen,  water  and  iodine  ;  when 
heated  in  close  tubes,  the  tubes  are  frequently  burst ;  but  Gay  Lussac 
succeeded  in  collecting  the  products,  which  were  equal  volumes  of  oxy- 
gen and  nitrogen  gases.  He  states  its  composition  to  be  100  acid  and 
10-94  ammonia,  or  two  volumes  gaseous  ammonia,  one  volume  iodine 
and  two  and  an  half  volumes  oxygen. — Thenard,  iii.  473. 

This  salt  may  be  obtained  by  adding  ammonia  to  iodic  acid  to  sat- 
uration, small  crystals  being  immediately  deposited. 

Hydrochlorate  or  Muriate  of  Ammonia — Atom.  Num.  52'45 — 
Symb.  (3H-f  N)+CCI+H)-^.  gr.  145  water=l. 

Known  in  commerce  as  Sal- Ammoniac,  a  name  given  to  it  by  the 
ancients,  because  it  was  found  in  great  quantities  near  the  temple  of 
Jupiter  Ammon. 

Crystallizes  ordinarily  in  long  needles,  which  appear  to  be  hexahe- 
dral  pyramids  ;  white,  of  a  very  sharp  taste  ;  soluble  in  three  parts  of 
water  at  603,  and  in  equal  parts  of  boiling  water  ;  exposed  to  heat  it 
melts  in  its  own  water  of  crystallization,  dries  and  sublimes  in  the 
form  of  white  vapours  ;  is  decomposed  by  the  fixed  alkalies  and  alka- 
line earths  ;  reddens  litmus  paper,  [Berzelius~\ ;  calcined  with  carbon- 
ate of  lime,  it  yields  solid  chloride  of  calcium,  volatile  carbonate  of 
ammonia  and  water. 

PREPARATION  AND  NATIVE  STATE.  Hydrochlorate  of  ammonia  is 
found  native  in  the  dung  of  certain  animals,  particularly  the  camel  ; 
and  in  human  urine.  It  appears  also  to  exist  in  small  quantities  in 
the  vicinity  of  volcanoes,  and  Dr.  Marcet  has  ascertained  that  it  ex- 
ists in  sea  water,  and  may  be  separated  by  sublimation  from  the  un- 
cristallizable  part,  called  bitt6rn.~Ph.il.  Trans.  1822.  454. 

This  salt  may  be  formed  directly,  by  mixing  over  mercury  equal 
measures  of  ammoniacal  gas,  and  muriatic  acid  gas,  which  are  entire- 
ly condensed  into  a  white  solid. 

The  common  sal-ammoniac  of  the  shops  is  prepared  by  a  circuitous 
process  from  an  impure  carbonate  of  ammonia,  obtained  from  the  dis- 
tillation of  bones  and  other  animal  matters.  This  carbonate  of  ammo- 
nia, by  being  kept  in  contact  with  sulphate  of  lime  and  water,  is  convert- 
ed into  sulphate  of  ammonia.  This  again  is  decomposed  by  muriate  of 
soda,  which  affords  muriate  of  ammonia  and  sulphate  of  soda.  The 
latter  salt  is  separated  by  priority  of  crystallization,  and  the  muriate 
of  ammonia  is  then  purified  by  being  once  or  twice  sublimed.  In  this 
way  it  is  usually  obtained  in  the  form  of  a  hard  elastic  cake. 

USES.  This  salt  is  employed  to  furnish  ammonia  and  the  carbo- 
nate of  ammonia ;  in  certain  metallurgic  operations  ;  in  tinning  the 
surface  of  copper  to  prevent  its  oxidation :  it  is  employed  also  in 
small  quantities  in  dyeing ;  in  medicine  as  a  stimulant,  and  when 
dissolved  in  nitric  acid,  forms  the  aqua  regia  of  commerce,  employed 
for  dissolving  gold,  instead  of  a  mixture  of  nitric  and  muriatic  acids. 

ACTION  ON  THE  ANIMAL  ECONOMY.  This  salt  is  poisonous  when  tak- 
en into  the  stomach,  or  applied  in  large  quantities  to  wounds.  It 
causes  vomiting,  convulsions  and  death. — Beck's  Med.  Juris.  502. 

REFERENCES.  Sal-ammoniac  and  its  manufacture,  Encyc.  Britannica 
Suppl.  A  volcanic  product  in  Centra^sTctcianfy  B^nde's  Jour.  x.  197. 


J(  UNIVERSH 


. 


142  NITROGEN. 

Aslley ,  improvements  in  the  manufacture  ofy  Repert.  of  Arts, %d  ser.  xii.  248. 
Manufacture  of,  in  Egypt,  Clarke's  Trav.  v.  23.  Parkes*  Chem.  Essays,  iv. 
on  Sal-ammoniac. 

Hydriodate  of  Ammonia. — Crystallizes  in  cubes,  which  are  more  sol- 
uble than  sal-ammoniac,  and  nearly  as  volatile,  subliming  in  close  ves- 
sels without  decomposition. 

PREPARATION.  The  hydriodate  of  ammonia  may  be  prepared  by 
combining  directly,  equal  volumes  of  hydriodic  acid  and  ammonia  in 
their  gaseous  state  ;  or  by  saturating  liquid  hydriodic  acid  with  carbon- 
ate of  ammonia. 

Hydrofluate  of  Ammonia.— Crystallizes  with  much  difficulty  ;  has  a 
very  sharp  taste  ;  when  heated  disengages  a  portion  of  ammonia,  pass- 
es to  an  acid  state  and  vaporizes  under  the  form  of  dense  and  very 
disagreeable  white  fumes,  at  a  temperature  scarcely  above  that  of  boil- 
ing water  ;  is  very  soluble  in  water  ;  is  decomposed  by  sulphuric  acid, 
with  brisk  effervescence  and  a  great  disengagement  of  heat. 

PREPARATION,  This  salt  may  be  prepared  by  adding  a  solution  of 
ammonia  to  the  hydrofluoric  acid,  allowing  a  slight  excess  of  ammo- 
nia, and  afterwards  evaporating  the  liquor  at  a  moderate  heat  in  a 
platinum  or  silver  vessel. 

REFERENCES.  Gay  Lussacand  Thenard,  Jour,  de  Phys.  January,  1C09. 
Repert.  of  Arts,  2d  ser.  xv.  90.  J.  Davy,  Repert.  of  Arts,  '^d  ser.  xxii.  77. 

Nitrate  of  Ammonia— Atom.  Mim.  71—  Symb.  (3H+N)+ 

(50+ N.) 

Known  by  the  older  chemists  under  the  name  of  Nit-rum  Flammnns. 

Crystallizes  in  various  forms  according  to  the  manner  in  which  its 
solution  has  been  evaporated  ;  if  at  a  temperature  below  100°  F.  in 
six-sided  prisms,  terminated  by  six-sided  pyramids  ;  if  boiled  down, 
its  crystals  are  thin  and  fibrous ;  and  when  the  evaporation  is  carried 
so  far  that  the  salt  immediately  concretes  on  a  glass  rod  in  cooling,  it 
then  forms  a  compact  and  shapeless  mass  ;  is  deliquescent,  (except 
when  evaporated  at  a  high  temperature,)  and  soluble  in  twice  its 
weight  of  water  at  60°  ;  has  an  acrid  and  bitter  taste ;  undergoes 
watery  fusion  when  exposed  to  heat,  giving  off  its  water  of  crystalliza- 
tion, and  a  small  portion  of  its  alkali  ;  when  gently  heated  in  a  retort 
is  converted  into  water  and  the  protoxide  of  nitrogen  ;  when  thrown 
into  a  red  hot  crucible  or  heated  to  the  temperature  of  600°  it  inflames 
or  explodes,  and  the  products  are  water,  nitrogen  and  the  deutoxide  of 
nitrogen,  the  inflammation  being  produced,  according  to  Thenard,  by 
the  rapid  combination  of  the  oxygen  of  the  nitric  acid  with  the  hydro 
gen  of  the  ammonia. 

The  composition  of  this  salt  varies  according  to  the  mode  of  its 
preparation.  — Davy. 

PREPARATION.  This  salt  has  not  been  found  native.  It  may  be 
procured  by  the  direct  union  of  ammonia  with  nitric  acid  ;  or  more 
easily  by  saturating  dilute  nitric  acid  with  carbonate  of  ammonia,  and 
evaporating  the  solution  until  a  pellicle  appears  on  the  surface.  The 
only  use  to  which  it  is  applied  is  in  the  process  for  obtaining  protoxide 
of  nitrogen. 


SULPHUR.  143 

SECTION  III. 

SULPHUR. 
Atom.  Num.  16—Symb.  S—Sp.  gr.  1'9S  water=L 

This  substance  has  been  known  from  the  most  remote  periods  of 
antiquity.  It  is  met  with  under  two  different  forms  ;  a  compact  solid, 
which  has  generally  the  shape  of  long  rolls  or  sticks,  called  roll  brim- 
stone; and  a  light  powder  called  floicers  of  sulphur. 

PROPERTIES.  Sulphur  is  of  a  light  yellow  colour,  and  when  melted 
emits  a  peculiar  odour  ;  is  insoluble  in  water,  and  tasteless ;  when 
heated  to  170°  F.  it  begins  to  evaporate,  and  to  produce  a  very  disa- 
greeable smell ;  at  185°  or  190°  it  begins  to  melt,  and  at  220°  is  com- 
pletely fluid,  but  if  the  heat  be  rapidly  increased,  it  loses,  at  350°  its 
fluidity,  and  becomes  firm,  and  of  a  deeper  colour.  It  regains  its  fluid- 
ity, if  we  reduce  the  temperature  ;  and  this  may  be  repeated  at  pleas- 
ure, in  close  glass  vessels,  if  the  changes  of  heat  be  not  too  slow  ; 
in  which  case  it  is  volatilized.  When  liquified  .sulphur,  of  the 
temperature  of  2*20°  is  slowly  cooled,  it  forms  a  fribrous  crystalline 
mass  ;  it  sublimes  at  the  temperature  of  60(P  ;  and  according  to  the 
greater  or  less  quickness  of  the  process,  and  the  size  of  the  condensing 
chambers,  may  be  collected  either  in  a  solid  form,  or  in  that  of  flow- 
ers.— [Thcnard,  i.  197.]  It  is  a  bad  conductor  of  electricity,  but  be- 
comes negatively  electric  by  heat  and  by  friction  j  and  is  in  a  high  de- 
gree doubly  refractive. 

Sulphur  may  be  crystallized. — The  crystalline  arrangement  is  gen- 
erally perceptible  in  the  centre  of  a  common  roll  of  sulphur  ;  and  by 
some  management,  regular  crystals  may  be  obtained.  To  attain  this 
end,  several  pounds  of  sulphur  should  be  melted  in  an  earthen  cruci- 
ble ;  and  when  partially  cooled,  the  outer  crust  should  be  pierced,  and 
the  crucible  quickly  inverted,  so  that  the  inner,  and  as  yet  fluid  parts, 
may  gradually  flow  out.  On  breaking  the  solid  mass,  when  quite 
cold,  crystals  of  sulphur  will  be  found  in  its  interior. 

M.  Mitscherlich  has  made  the  discovery  of  two  primary  forms  of 
sulphur.  The  one,  which  occurs  in  nature,  is  an  octahedron,  with  a 
rhombic  base  ;  the  other  produced  by  the  slow  cooling  of  fused  sul- 
phur, is  an  oblique  rhombic  prism. — Henry,  i.  403. 

Liquified  sulphur  suddenly  cooled,  is  variously  affected,  according-  to 
its  temperature — When  the  most  fluid  sulphur  is  suddenly  cooled,  it 
becomes  brittle,  but  the  thickened  sulphur,  similarly  treated,  remains 
soft,  and  more  soft  as  the  temperature  has  been  higher.  Thus  at 
230°,  sulphur  is  very  liquid  and  yellow,  and  cooled  suddenly  by  im- 
mersion in  a  large  quantity  of  water,  it  becomes  yellow  and  very 
friable  ;  at  374°,  it  is  thick  and  of  an  orange  colour,  and  by  cooling, 
becomes  at  first  soft  and  transparent,  but  soon  friable  and  of  the  ordi- 
nary appearance  ;  at  428°  it  is  red  and  viscid,  and  when  cooled,  soft, 
transparent  and  of  an  amber  colour  ;  and  at  the  boiling  point  it  is  of  a 
deep  brown  red  colour,  and  when  cooled,  very  soft,  transparent  and  of 
a  red  brown  colour. — Dumas,  Ann.  de  Ch.  et  de  P/i.  xxxv.  83. 

Solubility  of  sulphur. — Sulphur  is  completely  soluble  is  boiling  oil  of 
turpentine,  which  is  one  of  the  tests  of  its  purity.  It  is  also  soluble 
in  alcohol,  if  the  two  bodies  are  brought  into  contact  when  both  are 


144  SULPHUR. 

in  a  state  of  vapour.  On  pouring  this  compound  into  water,  the  sul- 
phur will  be  precipitated.  [For  a  description  of  the  details  of  the 
process,  see  Henry's  Chem.  i.  404.] 

Presence  of  hydrogen  in  sulphur. — The  presence  of  hydrogen  in  sul- 
phur, first  inferred  by  M.  Berthollet,  jun.  has  been  satisfactorily  prov- 
ed by  the  experiments  of  Sir  H.  Davy.  By  exposing  sulphur  to  the 
strong  heat  of  a  powerful  galvanic  battery,  he  found  that  sulphuretted 
hydrogen  was  disengaged.  But  the  quantity  was  so  small  that  he 
was  led  to  consider  it  nothing  more  than  an  accidental  ingredient. 
This  view  of  the  subject  is  also  embraced  by  Berzelius. — Ann.  de  Chim* 
Ixxix.  119. 

Milk  of  sulphur,  or  precipitated  sulphur  of  the  pharmacopeia,  some- 
times used  for  medicinal  purposes,  is  formed  by  precipitating  sulphur 
from  some  of  its  alkaline  solutions,  as  from  the  hydro-sulphuret  of  potas- 
sa,  by  an  acid.  When  washed  and  dried,  it  is  in  the  form  of  a  yellowish- 
grey  impalpable  powder,  and  is  considered,  by  Dr.  Thomson,  as  a  com- 
pound of  sulphur  and  water. 

PREPARATION  AND  NATIVE  STATE.  Sulphur  is  found  native  in  large 
quantities  in  the  vicinity  of  volcanoes,  and  as  an  article  of  commerce 
is  chiefly  brought  from  Sicily.  It  is  also  abundant  in  combination  in 
a  vast  number  of  native  sulphurets  and  sulphates.  Among  the  most 
important  of  these  are  the  sulphurets  of  iron,  lead,  mercury,  antimo- 
ny, copper  and  zinc. 

This  substance  is  prepared  artificially  by  being  separated  from  the 
earthy  substances  with  which  it  is  combined,  in  the  neighbourhood  of 
volcanoes,  or  from  the  compounds  which  it  forms  with  iron,  copper, 
&c.  In  the  former  case  it  is  exposed  to  heat,  in  large  pots,  well  cov- 
ered to  prevent  the  admission  of  air ;  when  fluid,  the  impurities  fall  to 
the  bottom,  and  it  is  then  poured  into  moulds,  thus  forming  the  cylin- 
ders. When  further  purification  is  necessary  a  greater  heat  is  applied 
and  the  sulphur  is  sublimed,  the  process  being  conducted  in  pots  hav- 
ing receivers  adapted  to  them,  in  which  the  vapour  is  condensed.  In 
the  latter  case  the  sulphurets  are  roasted  and  the  fumes  received  into 
chambers  of  brick  workr  where  the  sulphur  is  gradually  deposited ;  it 
is  then  purified  by  fusion  and  cast  into  sticks.  In  this  state  it  is 
known  in  commerce  by  the  name  of  roll  brimstone ,~  when  it  is  further 
purified  by  sublimation,  it  is  called  sublimed  sulphur,  or  flowers  of  sul- 
phur. 

USES.  Sulphur  is  extensively  employed  in  the  manufacture  of  sul- 
phuric acid  ;  in  that  of  gunpowder,  &c.  When  heated  to  300°  or 
350°  F.  and  poured,  at  that  temperature,  into  water,  it  becomes  tena- 
cious like  wax,  and  may  be  applied,  [as  was  done  by  Mr.  Tassie,]  to 
take  impressions  from  engraved  stones,  seals,  &c. 

In  medicine,  it  is  employed  both  as  an  external  application  and  as 
an  internal  remedy,  especially  in  diseases  of  the  skin. 

IMPURITIES. — Sulphur  sometimes  contains  earthy  impurities,  which 
can  be  readily  ascertained  by  heating  it  on  a  piece  of  platinum  leaf — 
when  the  sulphur  will  evaporate  and  leave  the  earthy  substances. 
Pure  sulphur  also  is  perfectly  soluble  in  boiling  oil  of  turpentine. 

Sometimes  arsenic  is  found  in  sulphur.  According  to  M.  M.  Geiger 
and  Reimann  the  minutest  quantity  can  be  detected  as  follows  :  A  cer- 
tain quantity  of  precipitated  sulphur,  flowers  of  sulphur,  or  ordinary- 
sulphur  finely  pulverized,  is  to  be  digested  with  ammonia  for  a  con- 
siderable time,  then  filtered,  and  afterwards  the  clear  liquid  acted  upon 


SULPHUR.     '  145 

by  muriatic  acid  in  excess.  If  a  yellow  precipitate  occurs,  it  is  an  in- 
dication of  the  presence  of  arsenic  ;  if  not,  the  liquid  is  to  be  evapo- 
rated until  only  a  few  drops  remain.  A  little  ammonia  is  then  to  be 
added ;  afterwards  a  small  quantity  of  muriatic  acid  ;  and  finally  a 
little  solution  of  sulphuretted  hydrogen.  If  there  be  the  smallest 
quantity  of  arsenic,  it  will  be  rendered  evident  by  a  yellow  precipi- 
tate. —Brande'  s  Jour.  N.  S.  v.  192. 

SULPHUR  AND  OXYGEN. 

Chemists  are  at  present  acquainted  with  four  compounds  of  oxygen 
and  sulphur,  all  of  which  have  acid  properties.  Their  composition  is 
shown  in  the  following  table. 

S.     O. 

Hypo-sulphurous  acid,         .         .         .         .  16-f-  8=24. 

Sulphurous  acid,          .         .         .         .         .  16+16=32. 

Hypo-sulphuric  acid,           ....          32+40=72. 
Sulphuric  acid, 16+14=40. 

Hyposulphurous  Acid — fltom.  Num.  24 — Symb.  O-f-S.  (or 
20+2  S=48.) 

This  acid,  like  the  hypo-nitrous,  exists  only  in  combination  with 
salifiable  bases,  forming  compounds,  which  were  first  examined  in 
1813,  by  Gay  Lussac,  and  were  called  by  him  Sulphuretted  Sulphites. 
Besides  other  methods  of  preparing  these  salts,  he  found  that  they 
might  be  obtained  by  digesting  the  solution  of  a  sulphite  with  sulphur, 
an  additional  quantity  of  which  might  thus  be  made  to  combine  with 
the  sulphurous  acid.  It  had  also  been  long  observed  by  Mr.  Higgins 
of  Dublin,  that  liquid  sulphurous  acid  dissolves  iron  without  efferves- 
cence ;  and  Berthollet  afterwards  showed  that  in  this  case  the  iron  is 
oxidized  at  the  expense  of  the  sulphurous  acid,  and  that  sulphur  is 
disengaged,  which  immediately  unites  with  the  sulphite  of  iron,  form- 
ing a  sulphuretted  sulphite. 

Dr.  Thomson  appears  to  have  been  the  first  who  took  a  correct  view 
of  these  phenomena.  The  new  compound  he  found  to  be  a  neutral 
salt,  containing  a  peculiar  acid  of  sulphur,  to  which  he  gave  the  name 
of  Hypo  sulphurous  Acid,  and  to  its  compounds,  that  of  Hyposulphites. — 
[Syst.  Cham.  5th  edit.]  This  view  has  been  confirmed  by  Mr.  Her- 
schel.  who  has  examined  these  compounds  with  great  ability. — [Edin. 
Phil.  Jour.  i.  8,  396.]  He  did  not,  however,  succeed  in  his  attempt  to 
exhibit  the  acid  in  a  separate  state  ;  nor  indeed  does  it  appear  capable 
of  existing  permanently  when  uncombined  with  a  base. 

From  the  experiments  of  Mr.  Herschel  and  his  own,  Dr.  Thom- 
son inferred  that  this  acid  is  a  compound  of  one  atom  oxygen+one 
atom  sulphur=24.  This  view  of  its  constitution,  although  oppo- 
sed by  a  subsequent  statement  of  Dr.  Thomson,  has  been  confirmed 
by  Rose.  It  is  somewhat  remarkable,  however,  that  while  its  ele- 
ments are  in  the  proportion  of  16  to  8,  the  atom  of  the  acid  is  not  24 
but  48.— Turner. 


146  SULPHUR. 

Sulphurous    Acid— Atom.   Num.    32—Sym?).    20+$— Sp. 
gr.  2222air=l. 

This  acid  appears  to  have  been  known  at  a  very  early  period,  though 
first  distinguished  as  a  separate  substance  by  Stahl.  It  was  also  ob- 
tained and  examined  by  Priestley  in  1774,  and  has  since  been  accu- 
rately analyzed  by  Gay  Lussac  and  Berzelius. 

PROPERTIES.  A  gaseous  and  invisible  acid  ;  has  a  sour  taste  and  a 
pungent  suffocating  odour  ;  extinguishes  burning  bodies  without  being 
itself  inflamed  ;  is  fatal  to  animal  life,  producing  a  violent  spasm  of 
the  glottis,  by  which  the  entrance  of  the  gas  into  the  lungs  is  prevent- 
ed, and,  even  when  diluted  with  air,  excites  cough  and  causes  a  pecu- 
liar uneasiness  about  the  chest ;  slightly  reddens  litmus  paper,  and 
then  slowly  bleaches  it ;  destroys  most  vegetable  colours  ;  is  absorbed 
by  water  to  the  extent  of  33  times  its  bulk  ;  is  readily  liquified  by  com- 
pression ;  by  combination  with  bases  it  forms  Sulphites. 

It  discharges  vegetable,  colours. — Vegetable  blues  are  reddened  by  sul- 
phurous acid  previous  to  their  being  discharged.  This  effect  may  be 
illustrated  in  a  striking  manner  by  holding  a  red  rose  over  the  blue 
flarne  of  a  common  match,  by  which  the  colour  will  be  discharged 
wherever  the  sulphurous  acid  comes  in  contact  with  it,  so  as  to  render 
it  beautifully  variegated,  or  entirely  white.  If  it  be  then  dipped  into 
water,  the  redness,  after  a  short  time,  will  be  restored.  As  the  bleach- 
ing powers  of  this  acid  are  quite  considerable,  it  is  much  used  in 
whitening  silk  and  straw  work.  It  also  removes  fruit  stains  from 
woollen  cloth. 

It  has  a  very  strong  attraction  for  oxygen. — Though  sulphurous  acid 
cannot  be  made  to  burn  by  the  approach  of  flame,  it  has  a  strong  at- 
traction for  oxygen,  nniting  witli  it  under  favourable  circumstances, 
and  forming  sulphuric  acid.  The  presence  of  moisture  is  essential  to 
this  change.  A  mixture  of  sulphurous  acid  and  oxygen  gases,  if  quite 
dry,  may  be  preserved  over  mercury,  for  any  length  of  time,  without 
acting  on  each  other.  But  if  a  little  water  be  admitted,  the  sulphurous 
acid  gradually  unites  with  oxygen,  and  disappears  entirely.  For  this 
reason,  a  solution  of  sulphurous  acid  in  water  cannot  be  kept,  unless 
atmospheric  air  be  carefully  excluded.  Many  of  the  chemical  proper- 
ties of  sulphurous  acid  are  owing  to  its  affinity  for  oxygen.  On  being 
added  to  a  solution  of  the  peroxide  of  iron,  it  takes  oxygen,  and  thus 
converts  the  peroxide  into  the  protoxide  of  that  metal.  The  solutions 
of  metals  which  have  a  weak  affinity  for  oxygen,  such  as  gold,  plati- 
num and  mercury,  are  completely  decomposed  by  it,  those  substances 
being  precipita'ed  in  the  metallic  form.  Nitric  acid  converts  it  in- 
stantly into  sulphuric  acid,  by  yielding  some  of  its  oxygen.  The 
peroxide  of  manganese  causes  a  similar  change,  and  is  itself  convert- 
ed into  the  protoxide  of  manganese,  which  unites  with  the  sulphuric 
acid. 

It  is  absorbed  by  water. — To  show  how  readily  this  gas  is  absorbed  by 
water,  let  a  small  bottle  be  filled  with  it  over  mercury  and  place  the 
thumb  on  the  mouth  of  the  bottle  and  take  it  off  under  water.  This 
fluid  will  instantly  combine  with  it,  and  be  forced  up  into  the  bottle 
with  explosive  violence  by  the  pressure  of  the  atmosphere.  Water 
may  be  easily  impregnated  with  sulphurous  acid  gas  by  passing  it  in  a 
current  through  this  fluid  ;  for  which  purpose  the  best  mode  is  to  em- 
ploy the  series  of  bottles  well  known  by  the  name  of  Woulfe's  appa- 


SULPHUR.  147 

ratus.     From  the  solution,  when  recently  prepared,  the  gas  may  be 
separated  by  heat,  but  not  by  congelation. 

It  is  readily  liquified  by  compression. — Of  all  the  gases,  sulphurous- 
acid  is  most  readily  liquified  by  compression.  According  to  Mr.  Fara- 
day, it  is  condensed  by  a  force  equal  to  the  pressure  of  two  atmos- 
pheres. M.  Bussy  has  obtained  it  in  a  liquid  form  under  the  usual  at- 
mospheric pressure,  b_y  passing  it  through  tubes  surrounded  by  a 
freezing  mixture  of  snow  and  salt.  The  Anhydrous  Liquid  acid  has  a 
density  of  1-45.  It  boils  at  14°  F.  From  the  rapidity  of  its  evapo- 
ration at  common  temperatures,  it  may  be  used  advantageously  for 
producing  an  intense  degree  of  cold.  M.  Bussy  succeeded  in  freezing 
mercury,  and  liquifying  several  of  the  gases,  by  the  cold  produced 
during  its  evaporation.  Ann.  of  Phil.  xxiv.  307.  Faraday,  Phil.  Trans, 
for  1823,  and  Ann.  of  Phil,  xxiii.  93. 

M.  de  la  Rive  has  recently  discovered  a  solid  compound  of  sulphur  • 
ous  acid  and  water,  procured  by  passing  moist  sulphurous  acid  gas 
through  a  recipient,  cooled  down  to  the  temperature  of  from  5°  to  14° 
F.  Colourless  crystals,  of  an  acid  and  not  unpleasant  taste,  are  con- 
densed on  the  inner  side  of  the  vessel.  This  compound  is  also  formed 
during  the  evaporation  of  liquid  sulphuric  acid ;  in  this  case  the  moist- 
ure of  the  atmosphere  contributes  to  its  formation ;  but  it  is  then 
mixed  with  ice. — Berzelius,  Trait,  de  Chim.  ii.  25. 

PREPARATION  AND  NATIVE  STATE.  Sulphurous  acid  is  found  native 
only  in  volcanic  countries,  and  most  generally  issuing  from  the  fissures 
of  lava.  It  is  constantly  disengaged  from  the  Solfatera  near  Naples, 
from  the  summit  of  Stromboli,  &c.  It  is  also  found  in  certain  hot 
springs  near  volcanoes  in  Italy. 

It  may  be  artificially  prepared  in  two  ways,  viz  : 

1.  By  burning  sulphur  at  a  low  temperature,  in  common  air,  under 
a  bell  glass — or  by  burning  sulphur  in  dry  oxygen  gas,  in  which  case 
it  is  the  sole  product  of  the  combustion. 

2.  By  heating  red  oxide  of  mercury  with  one  fourth  of  its  weight  of 
sulphur,  sulphurous  acid  is  produced,  in  the  proportion  of  about  a  cu- 
bic inch  for  every  five  grains  of  the  oxide. 

3.  By  boiling  one  part  by  weight  of  mercury  with  six  or  seven  of 
sulphuric  acid  to  dryness  in  a  glass  retort,  and  then  raising  the  heat, 
sulphurous  acid  gas  is  formed,  andmay  be  collected  and  preserved  over 
mercury.     Half  an  ounce  of  mercury  is  sufficient  for  the  production 
of  several  pints  of  the  gas.     In  this  instance  the  mercury  becomes 
oxidated  and   thus  deprives  the  sulphuric  acid  of  one   proportion   of 
oxygen,  and  reduces  it  to  sulphurous  acid.     The  sawings  of  wood  or 
powdered  charcoal  mixed  with  sulphuric  acid  in  a  retort,  also,  affords 
upon  the  application  of  heat,  a  large  quantity  of  this  gas. 

USES.  Sulphurous  acid  prepared  by  the  combustion  of  sulphur,  is 
much  used  for  bleaching  cotton  goods,  and  also  for  whitening  silk, 
wool  and  straw.  In  wine  countries  it  is  sometimes  used  to  check  vi- 
nous fermentation.  In  medicine  it  is  employed  in  some  diseases  of  the 
skin. 

REFERENCES.  Parkes'  Chem.  Essays,  art.  Blenching.  For  cases  illus- 
trciting  its  action  on  the  Animal  Economy ',  see  Beckys  Medical  Juris.  3d 
ed.  304. 


148  SULPHUR. 

Hyposidplmric  Add. — Atom.  Num.  72—Symb.  5O+2S. 

Discovered  by  Welter  and  Gay  Lussac,  in  1819. — Ann.  de  Chim.  et 
de  Phys.  x.  312. 

PROPERTIES.  A  colourless  liquid,  without  odour  even  in  the  great- 
est state  of  condensation,  by  which  circumstance  it  is  distinguished 
from  sulphurous  acid  ;  reddens  litmus ;  has  a  sour  taste,  and  forms 
neutral  salts  with  the  alkalies  ;  cannot  be  obtained  free  from  water ; 
its  solution,  if  confined  with  a  vessel  of  sulphuric  acid,  under  the  ex- 
hausted receiver  of  an  air  pump,  maybe  concentrated  till  it  has  a  den- 
sity of  1'347,  but  if  an  attempt  is  made  to  condense  it  still  further, 
the  acid  is  decomposed,  sulphurous  acid  gas  escapes,  and  sulphuric 
acid  remains  in  solution,  a  similar  change  being  still  more  readily  pro- 
duced if  the  evaporation  is  conducted  by  heat. 

PREPARATION.  The  process  recommended  by  Welter  and  Gay 
Lussac  for  obtaining  this  acid,  is  to  pass  a  current  of  sulphurous  aeid 
gas  through  water  containing  peroxide  of  manganese  in  fine  powder. 
The  manganese  yields  oxygen  to  the  sulphurous  acid,  thus  converting 
one  part  of  it  into  sulphuric,  and  another  part  into  the  hyposulphuric 
acid,  both  of  which  unite  with  the  protoxide  of  manganese.  To  the 
liquid,  after  filtration,  a  solution  of  pure  baryta  is  added  in  slight  ex- 
cess, which  precipitates  the  protoxide  of  manganese,  and  forms  an  in- 
soluble sulphate  of  baryta  with  the  sulphuric,  and  a  soluble  hyposul- 
phate  with  the  hyposulphuric  acid.  The  hyposulphate  of  baryta  is 
then  decomposed  by  a  quantity  of  sulphuric  acid  exactly  sufficient  for 
precipitating  the  baryta,  and  the  hyposulphuric  acid  is  left  in  solu- 
tion. This  solution  is  then  concentrated  by  evaporation,  until  its 
density  approaches  1'347. 

M.  Heeren  advises  that  when  sulphurous  acid  is  passed  over  black 
oxide  of  manganese,  the  oxide  should  be  finely  divided,  and  the  tem- 
perature low.  The  largest  portion  of  hyposulphuric  acid  is  formed  at 
the  commencement  of  the  operation. — Brandes  Jour.  N.  S.  ii.  473. 

REFERENCES.  Welter  and  Gay  Lussac,  on  Hyposulphuric  Acid  and  Hy 
posulphates,  Ann.  of  Phil.  xiv.  352. 

Sulphuric  Add. — Atom.  Num.  W—Symb.  3O+S. 

This  acid  has  been  known  ever  since  the  time  of  Basil  Valentine, 
who  appears  to  have  discovered  it  about  the  close  of  the  fifteenth 
century. 

Sulphuric  acid  exists  in  two  states  : — 1st,  a  dry  crystalline  solid, 
such  as  is  obtained  from  the  sulphuric  acid  of  Nordhausen  ;  2d,  a  li- 
quid combined  with  a  certain  proportion  of  water,  such  as  it  ordinarily 
exists  and  as  it  is  used  in  the  arts,  and  in  the  laboratory.  I  shull  no- 
tice each  of  these  separately. 

Anhydrous  Sulphuric  Acid. — Sometimes  called  Glacial  or  Fuming  Sul- 
phuric Acid. 

PROPERTIES.  A  white  and  opake  solid  ;  liquifies  at  66°  F.  and 
then  has  a  specific  gravity  of  1'97,  and  boils  at  a  temperature  between 
104°  and  122°,  forming,  if  no  moisture  is  present,  a  transparent  va- 
pour ;  when  exposed  to  the  air  unites  with  watery  vapour,  and  flies 
off  in  the  form  of  dense  white  fumes  ;  is  very  caustic  and  reddens 


SULPHUR.  149 

litmus  powerfully  ;  dissolves  sulphur  and  becomes  of  a  brown,  green 
or  blue  colour,  and  upon  the  addition  of  water,  the  sulphur  is 
deposited  and  the  acid  is  converted  into  ordinary  sulphuric  acid  ; 
dissolves  indigo  with  great  readiness,  the  solution  assuming  a  most 
beautiful  purple  colour,  and  hence  it  is  much  employed  for  this  pur- 
pose. 

PREPARATION.  This  acid  is  obtained  from  a  peculiar  kind  of  hy 
drous  sulphuric  acid,  manufactured  at  Nordhausen,  a  small  village  in 
Germany,  by  the  distillation  of  the  protosulphate  of  iron.  Gmelin 
has  procured  it  during  the  rectification  of  common  sulphuric  acid,  by 
changing  the  receiver  at  the  moment  when  it  is  filled  by  opake  vapours, 
and  surrounding  the  fresh  receiver  with  ice. — [Ann.  de  Chim.  et  de 
Phys.  xxxii.  223.]  Professor  Mosander,  of  Stockholm,  proposes  the 
following  very  simple  mode  of  preparing  it.  If  the  oxide  of  antimony 
be  treated  with  excess  of  sulphuric  acid  till  the  oxide  is  saturated,  and 
the  excess  of  acid  then  driven  off  by  a  low  temperature,  the  sulphate 
is  obtained  dry  and  crystallized.  If  this  salt  be  put  into  a  retort  and 
heated  to  dull  redness,  the  greater  part  of  the  acid  is  driven  off  in  an 
anhydrous  state  and  is  easily  condensed  in  acool  receiver. — Johnston's 
Re/tort.  On  this  acid  see  also — Thomson  s  First  Prin.  Bussy  in  Ann. 
of  Phil.  xxiv.  259,  and  Repert.  of  Arts,  2d  ser.  xlvi.  181. 

Hydrous  Sulphuric  Acid — Oil  of  Vitriol. 

PROPERTIES.  A  colourless,  dense,  oily  fluid,  one  of  the  strongest 
acids  with  which  chemists  are  acquainted  ;  is  powerfully  corrosive  ; 
decomposes  all  animal  arid  vegetable  substances  by  the  aid  of  heat, 
causing  deposition  of  charcoal  and  formation  of  water  ;  has  a  sour 
taste,  and  reddens  litmus  though  greatly  diluted  with  water  ;  boils  at 
62(P  F  and  has  a  specific  gravity,  in  its  most  concentrated  form,  of 
1'847,  or  a  little  higher,  never  exceeding  1-850  ;  has  a  great  affinity 
for  water,  uniting  with  it  in  every  proportion,  and  producing  during 
the  combination,  an  intense  heat ;  absorbs  watery  vapour  with  avidi- 
ty from  the  air,  and  on  this  account  is  employed  in  the  process  for 
freezing  water  by  its  own  evaporation  ;  freezes  at  —  15°  F.  but  when 
diluted  with  water,  so  as  to  have  a  specific  gravity  of  1-78,  it  congeals 
even  above  32J  F.  and  remains  in  the  solid  state,  according  to  Mr. 
Keir,  till  the  temperature  rises  to  45°  F.  but  when  mixed  with  ra- 
ther more  than  its  weight  of  water,  has  its  freezing  point  lowered  to 
—  36  ^  F. 

Sulphuric  Acid  chars  animal  and  vegetable  substances. — Hence  the  acid 
is  apt  to  acquire  a  brown  tinge,  from  particles  of  straw,  resin  or  other 
matter  that  may  accidentally  have  fallen  into  it.  Its  operation  in  this 
case  as  well  as  in  destroying  the  texture  of  the  skin,  and  in  forming 
others,  is  supposed  to  be  owing  to  its  affinity  for  water. 

It  has  a  great  affinity  for  water. — When  this  acid  is  suddenly  mixed 
with  water,  a  considerable  degree  of  heat  is  produced.  Four  parts, 
by  weight,  of  concentrated  sulphuric  acid,  and  one  of  water,  when 
mixed  together,  each  at  the  temperature  of  50 J  F.  have  their  tempera- 
ture raised  to  300°.  The  greatest  elevation  of  temperature,  Dr.  Ure 
finds  to  be  occasioned  by  the  sudden  mixture  of  7:i  parts,  by  weight, 
of  strong  sulphuric  acid  with  27  of  water.  A  diminution  of  bulk  also 
ensues ;  one  measure  of  acid  and  one  of  water  not  occupying  the 
space  of  two  measures  but  about  l-17th  less. 

It  takes  moisture  from  the  air,  even  at  a  boiling  temperature,  when 
it  is  concentrated  ;  and  hence  it  cannot  be  concentrated  so  well  in 


150  SULPHUR. 

an  open  as  in  a  close  vessel,  on  which  account  retorts  of  glass  or 
platinum,  are  used  for  the  last  stage  of  its  concentration  by  the  manu- 
facturers. 

Though  sulphuric  acid,  when  mixed  with  water  as  in  the  above 
cases,  produces  a  high  degree  of  heat,  a  mixture  of  2  parts  of  acid  and 
3  of  snow  reduces  the  mercury  in  Fahrenheit's  thermometer  to  —  23°. 
Hence  this  is  employed  as  a  freezing  mixture.  To  explain  these  re- 
sults, which  at  first  appear  contradictory,  it  is  sufficient  to  observe  : 
1st,  that  snow  or  ice,  in  passing  from  the  solid  to  the  liquid  state,  ab- 
sorbs caloric  ;  and,  2d,  that  sulphuric  acid,  in  combining  with  water, 
gives  out  caloric  ;  hence  either  heat  or  cold  is  produced  according  as 
water  is  employed  in  the  liquid  or  solid  form. 

Many  of  the  simple  non-metallic  combustibles  decompose  sulphuric  acid, 
ichcn  assisted  by  heat.  —  When  hydrogen  gas  and  sulphuric  acid  are 
made  to  pass  through  a  red  hot  porcelain  tube,  the  acid  is  completely 
decomposed,  and  there  results  water,  sulphurous  acid  or  sulphur,  ac- 
cording as  the  proportion  of  hydrogen  to  the  acid  is  greater  or  less. — 
When  the  hydrogen  is  in  excess,  and  the  heat  is  not  too  high,  sul- 
phuretted hydrogen  is  also  produced.  Sulphuric  acid  is  also  decom- 
posed by  carbon,  phosphorus  and  sulphur. 

PREPARATION  AND  NATIVE  STATE. — Though  sulphuric  acid  is  said  to 
have  been  found  native,  it  is  doubtful  whether  this  is  correct.  The- 
rtard  supposes  that  naturalists  have  mistaken  for  it  an  acid  sulphate. — 
[Trait,  de  Chim.  ii.  213.]  It  is,  however,  frequently  found  in  combi- 
nation with  various  bases,  as  lime,  potassa,  soda,  &c. 

The  process  for  forming  sulphuric  acid,  at  present  very  generally 
adopted,  is  by  burning  sulphur,  previously  mixed  with  one-eighth  of 
its  weight  of  nitrate  of  potassa.  The  mixture  is  burned  in  a  furnace  so 
contrived  that  the  current  of  air  which  supports  the  combustion,  con- 
veys the  gaseous  products  into  a  large  leaden  chamber,  the  bottom  of 
which  is  covered,  to  the  depth  of  several  inches,  with  water.  The 
nitric  acid  yields  oxygen  to  a  portion  of  sulphur,  and  converts  it  into 
sulphuric  acid,  which  combines  with  the  potassa  of  the  nitre  ;  while 
the  greater  part  of  the  sulphur  forms  sulphurous  acid,  by  uniting  with 
the  oxygen  of  the  air.  The  nitric  acid,  in  losing  oxygen,  is  converted 
into  the  deutoxide  of  nitrogen,  which,  by  mixing  with  air  at  the  mo- 
ment of  its  separation,  gives  rise  to  the  nitrous  acid  vapours.  The 
gaseous  substances  present  in  the  leaden  chamber  are,  therefore,  sul- 
phurous and  nitrous  acids,  atmospheric  air  and  watery  vapour.  And 
it  appears  that  the  sulphurous  is  converted  into  the  sulphuric  acid,  by 
the  oxygen  of  the  air,  and  that  the  combination  is  not  effected  di- 
rectly, but  through  the  medium  of  the  nitrous  acid.  For  details  of 
this  explanation  see  Davy's  Elements  and  Webster's  Brande.  An  ac- 
count of  the  successive  improvements  in  the  manufacture  of  sulphuric 
acid,  will  be  found  in  Parkes'  Chemical  Essays.  Mr.  Reid,  in  his 
Practical  Chemistry,  describes  an  apparatus  which  illustrates  in  a  very 
happy  manner  the  theory  of  the  formation  of  this  acid. 

Although  sulphuric  acid,  as  ordinarily  prepared,  answers  in  general 
the  purpose  of  the  artist,  it  is  never  quite  pure.  It  contains  some 
sulphate  of  potash  and  of  lead,  the  former  derived  from  the  nitric  em- 
ployed in  making  it,  the  latter  from  the  leaden  chamber.  To  sepa- 
rate these  impurities,  the  acid  should  be  distilled  from  a  glass  or  pla- 
tinum retort.  The  former  may  be  used  with  safety,  by  putting  some 
fragments  of  platinum  leaf  into  it,  which  causes  the  acid  to  boil  free- 


SULPHUR.  151 

ly  on  the  application  of  heat,  without  danger  of  breaking  the  vessel. — 
Faraday,  Chem.  Manip.  sect.  409. 

The  strength  of  sulphuric  acid  is  best  judged  of  by  saturating  a 
known  quantity  with  an  alkali,  and  it  may  be  assumed  as  sufficiently 
correct,  that  100  grains  of  dry  sub-carbonate  of  soda  neutralize  92 
grains  of  pure  liquid  sulphuric  acid  ;  or  that  1 00  grains  of  the  acid 
require  108  or  108'5  of  the  sub-carbonate  for  saturation.  The  strength 
may  also  be  judged  of  by  its  specific  gravity.  Mr.  Dalton  has  pub- 
lished a  table,  exhibiting  the  specific  gravity  and  boiling  point  of  acid 
of  various  strengths. — New  System  of  Chem.  Philosophy.  See  also 
Henry  s  Che^i. 

ADULTERATION.  The  presence  of  sulphuric  acid  may  always  be  de- 
tected by  the  white  insoluble  precipitate  which  it  forms  when  added  to 
any  soluble  salt  of  baryta.  If  the  acid  is  coloured  it  indicates  the  pre- 
sence of  organic  matter.  If  when  diluted  with  water,  it  becomes  tur- 
bid, we  may  infer  the  presence  of  sulphate  of  lime,  sulphate  of  lead  or 
some  such  salt.  But  the  amount  and  nature  of  these  impurities  may 
be  more  satisfactorily  determined  by  heating  a  portion  of  acid  in  a  pla- 
tinum spoon  ;  the  pure  acid  will  be  entirely  volatilized,  but  the  salts, 
if  it  contain  any,  will  remain  and  may  be  subsequently  examined. 

USES.  The  uses  of  sulphuric  acid  are  very  numerous.  1.  It  is  that 
by  means  of  which  we  obtain  almost  all  the  other  acids  employed  in 
the  laboratory  or  in  the  arts.  2.  To  extract  soda  from  common  salt. 
3.  In  the  manufacture  of  alum,  sulphate  of  iron,  to  dissolve  indigo, 
in  the  manufacture  of  chlorine,  and  in  various  chemical  processes, 
Indeed  it  is  one  of  the  most  common  agents  employed  by  chemists 
and  artists. 

REFERENCES.  On  the  modes  of  manufacturing  Sulphuric  Acid,  see  Chap- 
tal^s  Chemistry ',  applied  to  the  Arts,  iii.  21,  and  Par/ces1  Chemical  Essays, 
ii.  273. 


SULPHUR    AND    CHLORINE. 

Chloride  of  Sulphur. — Atom.  Num.  51*15 — Symb.  Cl+S — 
8p.gr.  1-687  water=l. 

This  compound  was  discovered  by  Dr  Thomson  in  1804,  and  was 
subsequently  examined  by  Bertliollet,  Davy  and  Dumas. 

PROPERTIES.  A  liquid  appearing  red  by  reflected  and  yellowish- 
green  by  transmitted  light;  volatile  below  200D  F.,  and  condenses 
again  without  change  on  cooling  ;  emits  acrid  fumes  when  exposed  to 
the  air,  which  irritate  the  eyes  powerfully,  and  have  an  odour  some- 
what resembling  sea-weed,  but  much  stronger  ;  reddens  tincture  of 
turnsol  powerfully  ;  boils  readily  when  heated  in  a  retort,  but  is  not 
changed  ;  acts  with  energy  on  water,  mutual  decomposition  ensues, 
the  water  becomes  cloudy  from  the  deposition  of  sulphur,  and  a  solu- 
tion is  obtained,  in  which  muriatic,  sulphurous,  and  sulphuric  acids, 
may  be  detected. 

PREPARATION.  Chloride  of  sulphur  may  be  most  conveniently  pre- 
pared by  passing  a  current  of  chlorine  gas  over  flowers  of  sulphur 
gently  heated.  Direct  combination  takes  place,  and  the  product  is 
obtained  under  the  form  of  a  liquid  as  above  described. 

Some  chemists  regard  this  compound  as  an  acid,  and  propose  to 


152  SULPHUR. 

name  it  Chloro-sulphuric  Acid,  because  it  reddens  the  tincture  of  turn- 
sol.  This  effect,  however,  is  more  properly  ascribed  to  the  sudden 
formation  of  muriatic  or  sulphurous  acid.  Besides,  the  chloride  of 
sulphur  does  not  combine  with  salifiable  bases. 

Berzelius  describes  two  compounds  of  chlorine  and  sulphur.  One 
of  which  he  calls  Cklorure  sulfurique ;  the  other  Chlorure  sulfur  eux. 

REFERENCES.     Thomson  on  the  composition  of  Chloride  of  Sulphur,  Ann. 

of  Phil.  xv.  408.     Berzelius,  T    .    de  Chim.  i.  283. 
'     raite 

SULPHUR    AND    BROMINE. 

Bromide  of  Sulphur. 

On  pouring  bromine  on  sublimed  sulphur,  combination  ensues,  and 
a  fluid  of  an  oily  appearance  and  reddish  tint  is  generated.  In  odour 
it  somewhat  resembles  chloride  of  sulphur,  and  like  that  compound 
emits  white  vapours  when  exposed  to  the  air,  but  its  colour  is  deep- 
er. It  reddens  litmus  paper  faintly  when  dry,  but  strongly  if  water  is 
added.  Cold  water  acts  slowly  upon  the  bromide  of  sulphur  ;  but  at 
a  boiling  temperature,  the  action  is  so  violent  that  a  slight  detonation 
occurs,  and  three  compounds,  hydrobromic  and  sulphuric  acids,  and 
sulphuretted  hydrogen  are  formed.  The  formation  of  these  substan- 
ces is  of  course  attributable  to  decomposition  of  water,  and  the  union 
of  its  elements  with  bromine  and  sulphur.  Bromide  of  sulphur  is  like- 
wise decomposed  by  chlorine,  which  unites  with  sulphur,  and  displaces 
bromine. — Turner. 

SULPHUR    AND    IODINE. 

Iodide  of  Sulphur. 

^""Sulphur  unites  readily  with  iodine,  but  with  less  energy  than  with 
phosphorus.  A  gentle  heat  is  necessary  to  effect  the  combination. — 
The  resulting  compound  is  in  the  form  of  brilliant  rays,  resembling 
sulphuret  of  antimony.  It  decomposes  with  facility  when  exposed  to 
a  temperature  a  little  more  elevated  than  that  at  which  it  is  formed,  the 
iodine  separating  in  the  form  of  vapour. 

This  compound  was  first  described  by  Gay  Lussac. — Ann.  de  Chim. 
xci. 

SULPHUR    AND    HYDROGEN. 

According  to  some  chemists,  these  substances  combine  in  two  pro- 
portions, forming  what  were  originally  termed  Sulphuretted  Hydrogen 
and  Supersulphuretted  Hydrogen.  But  the  nature  of  the  latter  has  not 
been  clearly  settled.  Both,  however,  are  allowed  to  possess  acid  pro- 
perties, and  some  German  chemists  have  proposed  for  the  former  the 
name  of  Hydrothionic  Acid.  This  is  preferable  to  the  name  of  Hydro- 
sulphuric  acid,  given  to  it  by  Gay  Lussac,  which  would  be  more  pro- 
perly applied  to  liquid  sulphuric  acid.  Should  the  supersulphuretted 
hydrogen  prove  to  be  a  distinct  substance,  it  may  be  called  Hydrothion- 
ous  Acid. 


SULPHUR.  153 

Hydrothionic  Acid. — Atom.  Num.  17 — Symb.  H+S— *  Sp.  gr. 
1-1805  air=l. 

SYN.  Sulphuretted  Hydrogen,  Scheele.  Hydrosulphuric  Acid,  Gay 
Lussac.  Su/fide  Hydrique,  Berzelius. 

Discovered  by  Scheele  in  1777. 

PROPERTIES.  A  colourless  gas,  having  a  highly  offensive  taste  and 
odour,  similar  to  that  of  putrifying  eggs  or  the  water  of  sulphurous 
springs  ;.  is  compressed  into  a  liquid  under  a  pressure  of  17  atmos- 
pheres, at  50°  F.,  resuming  the  gaseous  state  as  soon  as  the  pressure  is 
removed  ;  is  very  injurious  to  animal  life  ;  extinguishes  all  burning 
bodies,  but  the  gas  takes  fire  when  a  lighted  candle  is  immersed  in  it, 
and  burns  with  a  pale  blue  flame ;  with  oxygen  gas  forms  a  mixture 
which  detonates  by  the  application  of  flame  or  the  electric  spark  ; 
reddens  litmus  feebly,  and  forms  salts  with  the  alkalies  called  Hydro- 
sulphurets  or  Hy dro sulphates ;  is  absorbed  by  water  when  agitated, 
or  when  recently  boiled,  from  which  the  gas  may  be  expelled  without 
change ;  is  partly  decomposed  when  submitted  to  heat  in  a  porcelain 
tube,  a  portion  of  sulphur  and  hydrogen  separating,  the  first  in  a  solid 
and  the  second  in  a  gaseous  state. 

It  is  decomposed  by  Chlorine  and  Iodine. — Sulphuretted  hydrogen  is 
decomposed  by  chlorine  and  iodine  in  consequence  of  their  great  affini- 
ty for  hydrogen,  and  the  former  is  often  employed  as  a  means  of  pu- 
rifying places  which  have  been  rendered  noxious  by  this  gas.  The  re- 
sult of  the  action  of  chlorine  is  muriatic  acid,  that  of  the  action  of 
iodine,  hydriodic  acid. 

It  acts  upon  most  of  the  metals. — Sulphuretted  hydrogen  acts  upon 
most  of  the  metals  ;  the  gas  is  decomposed,  the  sulphur  combines 
with  the  metals,  and  the  hydrogen  is  liberated.  Hence  it  is  used  as 
a  test  of  the  presence  of  metals  in  solution. 

It  is  absorbed  by  water. — Water,  when  agitated  or  under  pressure, 
absorbs  three  times  its  volume  of  this  gas,  forming  a  transparent  and 
colourless  liquid,  with  the  taste  and  odour  of  the  gas.  But  when  ex- 
posed to  the  air,  it  becomes  covered  with  a  pellicle  of  sulphur.  Sul- 
phur is  even  deposited  when  the  water  is  kept  in  well  closed  bottles. 

On  the  addition  of  a  few  drops  of  nitric  or  nitrous  acid  to  the  wa- 
tery solution,  sulphur  is  instantly  precipitated.  In  this  case  the  oxy- 
gen of  the  acid  combines  with  the  hydrogen  of  the  gas,  and  the  sul- 
phur is  separated.  The  gas  itself,  also,  is  decomposed  when  trans- 
mitted through  sulphuric,  nitric  or  arsenic  acids.  [BrandesJour.il. 
152.]  If  a  drachm  of  fuming  nitric  acid  is  poured  into  a  bottle  full 
of  sulphuretted  hydrogen  gas,  a  bluish  white  flame  passes  rapidly 
through  the  vessel,  sulphur  and  nitrous  acid  fumes  make  their  ap- 
pearance, and  of  course  water  is  generated. 

Liquid  Sulphuretted  Hydrogen. — Mr.  Faraday  obtained  sulphuretted 
hydrogen  in  a  liquid  form  by  producing  it  under  pressure.  It  was 
then  colourless,  limpid  and  excessively  fluid.  Ether  when  compar- 
ed with  it  in  similar  tubes,  appeared  tenacious  and  oily.  It  did  not 
seem  more  consistant  at  0°  than  at  45°  F.,  and  when  raised  from  the 
former  to  the  latter  temperature,  the  only  effect  was,  that  part  of  the 
liquid  rose  in  vapour,  and  its  quantity  diminished.  When  a  tube 
containing  it  was  opened  under  water,  the  liquid  rushed  immediately 
into  gas,  which  when  collected,  had  all  the  properties  of  sulphuret- 


154  SULPHUR. 

ted  hydrogen.  The  refractive  power  of  the  liquid  appeared  rather 
greater  than  that  of  water  ;  it  decidedly  surpassed  that  of  sulphurous 
acid.  By  a  small  guage,  introduced  into  the  tube  in  which  it  was 
produced,  the  pressure  of  its  vapour  was  nearly  equal  to  17  atmos- 
pheres at  50°  F.—Mul.  Trans.  1823,  192. 

NATIVE  STATE  AND  PREPARATION.  Sulphuretted  hydrogen  is  given 
off  in  small  quantities  from  various  springs  denominated  sulphur- 
ous. Also  from  many  substances  undergoing  the  process  of  putrefac- 
tion, as  eggs,  &c.,  and  hence  its  peculiar  odour  can  often  be  observ- 
ed in  the  vicinity  of  sinks  and  sewers.  Its  presence  can  also  be  de- 
tected by  its  effects  in  blackening  silver  or  other  metallic  substances. 

This  gas  can  readily  be  prepared  by  presenting  sulphur  to  nascent 
hydrogen.  Any  of  the  sulphurets  of  the  alkaline  metals  will  furnish 
it  by  the  mere  addition  of  water.  It  may  also  be  obtained  by  adding 
diluted  sulphuric  acid  to  sulphuret  of  iron  ;  or  more  conveniently  by 
heating  bruised  sulphuret  of  antimony  in  muriatic  acid.  It  may  be 
procured  over  water,  though  by  agitation  that  fluid  absorbs  thrice  its 
bulk.  The  use  of  metallic  vessels  should  of  course  be  avoided  in  pro- 
curing this  gas. 

TESTS.  Sulphuretted  hydrogen  is  readily  distinguished  from  other 
gases  by  its  odour.  The  most  delicate  chemical  test  of  its  presence 
is  carbonate  of  lead  (white  paint,)  mixed  with  water  and  spread  up- 
on a  piece  of  white  paper.  So  minute  a  quantity  of  sulphuretted  hy- 
drogen may  by  this  means  be  detected,  that  one  measure  of  the  gas 
mixed  with  20,000  times  its  volume  of  air,  hydrogen  or  carburetted  hy- 
drogen, gives  a  brown  stain  to  the  whitened  surface. — Henry's  Chcm. 
i.  467. 

ACTION  ON  THE  ANIMAL  ECONOMY.  Sulphuretted  hydrogen  is  one  of 
the  most  deleterious  gases  with  which  we  are  acquainted.  According 
to  the  experiments  of  Dupuytren  andThenard,  the  presence  of  l-1500th 
of  sulphuretted  hydrogen  in  air,  is  instantly  fatal  to  a  small  bird  ; 
.  l-800th  killed  a  middle  sized  dog,  and  a  horse  died  in  an  atmosphere 
which  contained  1 -250th  of  its  volume.  Chaussier  has  even  proved 
that  if  this  gas  be  made  on  the  cutaneous  surface  of  animals,  it  is  suffi- 
cient to  cause  their  death. — Thenard,  iv.  575.  Jour,  dc  Medicine,  de 
M.  Leroux,  fyc. 

USES.  Sulphuretted  hydrogen  is  used  sometimes  in  medicine,  as, 
for  example,  in  the  form  of  baths,  for  certain  cutaneous  eruptions.  It 
is  also  employed  by  the  laboratory  as  a  re-agent  for  detecting  the  pres- 
ence of  the  metals. 

REFERENCES.  This  compound  has  been  the  subject  of  numerous  researches 
by  Uertkollet,  Chassier,  Dnpuytren,  Davy,  Gay  Lussac  and  Thenard. — 
Berthollet  has  made  it  almost  a  complete  study,  Ann.  de  Chim.  xxv.  Chas- 
itier,  Dupuytren  and  Thenard  /iave  examined  its  deleterious  action  upon  the 
animal  economy — Jour,  de  Medicine.  Davy,  Gay  Lutwc  and  Thenard,  have 
examined  its  ehendcal  properties — Recherches  Physico  ChLnijites,  i. 

Ilydrothionous  Add — Atom.  Num.  33 — Symb.  H-J-2S. 

SYN.  Super sulphuretted  Hydrogen. — Scheele.  Per-  or  Bi-suJphurettcd 
Hydrogen. 

This  substance  was  discovered  by  Scheele,  afterwards  examined  by 


SULPHUR.  155 

Berthollet.  ( Ann.  de  Chim.  xxv.)  and  still  more  recently  by  Thenard. 
(Ann.  dc  Chim.  xlviii.  79,  or  Johnston's  Report.}  It  may  be  convenient- 
ly made  by  boiling  equal  parts  of  recently  slacked  lime  and  flowers  ot 
sulphur,  with  five  or  six  of  water,  when  a  deep  orange  yellow  solution 
is  formed,  which  contains  a  hydro-sulphuret  of  lime  with  excess  of 
sulphur.  On  pouring  this  liquid  into  strong  muriatic  acid,  a  copious 
deposition  of  sulphur  takes  place  ;  and  the  greater  part  of  the  sul- 
phuretted hydrogen,  instead  of  escaping  with  effervescence,  is  retain- 
ed by  the  sulphur.  After  some  minutes,  a  yellowish  semi-fluid  matter 
like  oil,  collects  at  the  bottom  of  the  vessel,  which  is  the  bisulphuret- 
ted  or  super-sulphuretted  hydrogen. 

PROPERTIES.  A  viscid  substance  ;  has  the  peculiar  taste  and  odour 
of  the  sulphuretted  hydrogen,  but  in  an  inferior  degree  ;  unites  with 
salifiable  bases,  forming  salts,  denominated,  Sulphuretted  Hydrosulphu- 
rets,  (or  Hydrolhionites);  is  inflammable  and  burns  in  the  air  with 
the  smell  of  sulphurous  acid  ;  when  gently  heated,  is  resolved  into 
sulphur  and  sulphuretted  hydrogen,  and  from  the  facility  with  which 
this  decomposition  is  effected,  the  history  of  this  substance  is  still  im- 
perfect. 

The  salts  of  the  bi-sulphuretted  hydrogen  may  be  prepared  by  di- 
gesting sulphur  in  solutions  of  the  alkaline  or  earthy  hydro-sulphurets. 
They  are  also  generated  when  alkalies  or  alkaline  earths  are  boiled 
with  sulphur  and  water.  These  salts  absorb  oxygen  from  the  air,  arid 
pass  gradually  into  hyposulphites.  A  similar  change  is  speedily  ef- 
fected by  the  action  of  sulphurous  acid.  Dilute  muriatic  and  sulphu- 
ric acids  produce  in  them  a  deposition  of  sulphur,  and  evolution  of 
sulphuretted  hydrogen. 

SALTS    OF    AMMONIA    AND    THE    ACIDS    CONTAINING    SULPHUR. 

Hyposulphite  of  Ammonia. — This  salt  has  a  pungent  and  excessively 
bitter  taste  ;  it  does  not  readily  crystallize  ;  when  heated  it  burns  with 
a  feeble  flame  and  evaporates. — Edin.  Phil.  Jour.  i. 

Sulphite  of  Ammonia. — Crystallizes  in  six-sided  prisms,  terminated 
by  six-sided  pyramids,  or  in  four-sided  rhomboidal  prisms,  terminated 
by  three-sided  summits  ;  has  a  cool,  penetrating  and  somewhat  sul- 
phurous taste  ;  is  soluble  in  its  own  weight  of  cold  water  ;  or  in  less 
than  an  equal  weight  of  boiling  water  ;  attracts  moisture  from  the  air, 
and  rapidly  passes  to  the  state  of  a  sulphate. 

Though  this  salt  usually  contains  water,  it  may  be  obtained  anhy- 
drous.— Dobereiner  in  Phil.  Mag.  and  Ann.  ii.  389. 

Sulphate   of  Ammonia — Atom.  Num.  66 — Symb.  (3H+N) 
+(30+S)+lAq. 

SYN.  Secret  Sal- Ammoniac,  Glauber.     Viiriolated  Ammoniac. 

PROPERTIES.  Crystallizes  usually  in  small  six-sided  prisms,  whose 
planes  are  unequal,  terminated  by  six-sided  pyramids  ;  has  a  sharp  and 
bitter  taste  ;  is  soluble  in  twice  its  own  weight  of  water  at  60°  F. 
and  in  its  own  weight  of  boiling  water  ;  when  exposed  to  the  air,  slow- 
ly attracts  moisture  ;  when  heated,  first  decrepitates,  then  melts,  and 
is  converted  into  an  acid  sulphate ;  at  a  red  heat  it  is  completely  de- 
composed, nitrogen  is  disengaged,  as  well  as  water  and  the  acid  sul- 


156  PHOSPHORUS. 

phate  of  ammonia  which  vapourizes  in  the  form  of  a  white  cloud  ;  it  is 
also  decomposed  by  potassa,  soda,  &c. 

PREPARATION  AND  NATIVE  STATE.  This  salt  is  sometimes  found  na- 
tive in  the  vicinity  of  volcanoes.  In  the  laboratory  it  is  obtained  by 
adding  excess  of  ammonia  to  dilute  sulphuric  acid,  and  evaporating 
the  solution;  or  by  saturating  dilute  sulphuric  acid  by  carbonate  of 
ammonia,  or  by  decomposing  muriate  of  ammonia  by  sulphuric  acid. 
In  the  arts  it  is  obtained  in  large  quantities  by  treating  sulphate  of 
lime  with  the  carbonate  of  ammonia,  procured  during  the  distillation 
ef  animal  matter. 

Hydrothionate  of  Jlmmonia. — Atom.  Num.  34 — Symb. 

(3H+N.)+(H+S.) 

SYN.  Hydrosulphuret  of  Ammonia.  Hydrosulphate  of  Ammonia. 
— Thenard. 

PROPERTIES.  When  perfectly  pure,  this  substance  occurs  in  needle 
form  crystals,  which  are  transparent  and  colourless  ;  is  very  volatile, 
and  when  kept  in  a  bottle,  sublimes  gradually  to  the  top  of  the  ves- 
sel, where  it  crystallizes  in  long  transparent  plates,  by  which  means 
it  is  freed  from  any  impurities  which  it  may  contain  ;  when  exposed  to 
the  air  it  assumes  a  yellow  colour,  absorbs  oxygen,  and  passes  to  the 
state  of  a  hydroguretted  sulphuret ;  mixed  with  excess  of  ammonia, 
it  dissolves  speedily,  and  produces  a  considerable  degree  of  cold. 

PREPARATION.  Pure  hydro-sulphuret  of  ammonia  may  be  obtained 
by  combining  ammoniacal  gas  and  sulphuretted  hydrogen  gas  at  a  low 
temperature.  For  details  concerning  the  preparation  of  this  corn- 
pound,  see  Thenard,  iii.  477. 

When  sulphuretted  hydrogen  gas  is  passed  through  solution  of  am- 
monia, a  substance  is  obtained  which  is  commonly  called  Liquid  Hy- 
drosulphuret of  Ammonia  ;  and  which  is  much  employed  in  the  labora- 
tory as  a  test.  It  is  of  a  yellowish  colour,  and  rapidly  decomposes 
when  exposed  to  the  air  or  to  heat. 

Hydrothionitc  of  Jlmmonia. 

SYN.  Hydroguretted  Sulphuret  of  Ammonia. — Thomson  and  The- 
nard. 

A  liquid  of  the  consistence  of  syrup,  with  a  taste  and  odour  similar 
to  that  of  the  hydrosulphuret  of  ammonia.  But  this  as  well  as  the 
other  compounds  of  this  acid,  is  still  imperfectly  understood.  See  p. 
155.  And  for  further  particulars,  see  Thomson's  or  Thenard' s  Chem- 
istry and  HerscheVs  Paper  in  Edin.  Phil.  Jour.  i.  13. 

SECTION  IV. 

PHOSPHORUS. 
Atom.  Num.  15-7 — Symb.  P — Sp.  gr.  1-770  water=l. 

Phosphorus  was  discovered  by  Brandt,  an  alchemist  of  Hamburg,  in 
1669,  but  it  was  not  until  Scheele  published  his  process  for  obtaining 
it,  nearly  a  century  afterwards,  that  it  became  sufficiently  common  to 
be  accurately  examined. 


PHOSPHORUS. 

PROPERTIES.  Phosphorus  is  transparent  and  almost  colourless  ;  is 
so  soft  that  it  may  be  cut  with  a  knife,  and  the  cut  surface  has  a  waxy 
lustre ;  is  highly  inflammable,  undergoing  a  slow  combustion,  when 
exposed  to  the  air  at  common  temperatures  ;  fuses  at  the  temperature 
of  108°  F.  and  sublimes  at  550°  F. ;  inflames  spontaneously  in  chlo- 
rine ;  when  gently  heated,  burns  very  brilliantly  in  oxygen  gas ;  is 
soluble  in  ether,  alcohol,  olive  oil,  &c.  and  communicates  luminosity 
to  these  substances  ;  decomposes  nitrous  acid,  with  combustion  ;  is 
poisonous  when  taken  into  the  stomach  ;  by  carefully  fusing  and  cool- 
ing a  large  quantity  it  may  be  crystallized  in  rhombic  dodecahedrons. — 
Mitschertich,  in  Phil.  Mag.  and  Jinn.  iii.  154. 

Combustion  of  Phosphorus  in  air  and  in  oxygen. — Phosphorus  when 
brought  into  contact  with  air  or  oxygen  gas  at  low  temperatures,  gives 
out  white  vapours  and  a  peculiar  alliaceous  smell, — appears  luminous 
in  the  dark,  and  is  gradually  consumed.  Hence  it  should  always  be 
kept  under  water.  If  a  stick  of  phosphorus  be  put  into  a  jar  of  air 
inverted  over  water,  the  volume  gradually  diminishes,  and  if  the  tem- 
perature of  the  air  is  at  6CP  F.  the  whole  of  the  oxygen  will  be  with- 
drawn in  the  course  of  12  or  24  hours.  The  residue  is  nitrogen,  con- 
taining about  l-40th  of  its  bulk  of  the  vapour  of  phosphorus.  It  is  re- 
markable that  the  slow  combustion  of  phosphorus  does  not  take  place 
in  pure  oxygen,  unless  its  temperature  be  about  80°  F. ;  but  if  the 
oxygen  be  rarified  by  diminished  pressure,  or  diluted  with  nitrogen,  hy- 
drogen or  carbonic  acid,  then  the  oxydation  occurs  at  60°  F.  accom- 
panied with  the  extrication  of  light  and  heat.  The  presence  of  cer- 
tain gaseous  substances,  even  in  very  small  quantities,  has  been  found 
by  Mr.  Graham,  to  have  a  remarkable  effect  in  preventing  the  slow 
combustion  of  phosphorus. — Jour,  of  Science,  N.  S.  vi.  83. 

But  though  phosphorus,  in  a  solid  state,  acts  with  very  little  energy 
upon  oxygen  gas,  the  case  is  different  when  the  phosphorus  becomes 
liquid — then  it  absorbs  and  solidifies  this  gas  with  great  rapidity — 
and  there  results  phosphoric  acid,  with  much  heat,  and  a  very  vivid  disen- 
gagement of  light.  This  may  be  shown  by  filling  a  small  glass  tube 
with  mercury  and  introducing  into  it  a  small  quantity  of  well  dried 
phosphorus.  The  phosphorus,  being  lighter  than  the  mercury,  ascends 
to  the  upper  part  of  the  tube,  where  it  may  be  melted  by  a  small  spirit 
lamp  or  a  piece  of  burning  charcoal.  Oxygen  gas  is  now  passed  into 
the  tube,  bubble  by  bubble,  each  one  on  corning  into  contact  with  the 
phosphorus  disappearing  in  an  instant,  and  producing  a  flash  of  light, 
which  the  eye  is  scarcely  able  to  support. — [  T/ienard.  ]  This  fact  may 
also  be  shown  by  throwing  some  pieces  of  phosphorus  in  hot  water, 
and  then  directing  a  stream  of  oxygen  gas  upon  it. 

Phosphorus  is  inflamed  by  the  application  of  a  very  gentle  heat. — Ac- 
cording to  Dr.  Higgins  a  temperature  of  60°  F.  is  sufficient  to  set  it  on 
fire,  when  perfectly  dry.  It  burns,  when  heated  to  about  148°  F.  with 
a  very  brilliant  light,  a  white  smoke,  and  a  suffocating  smell,  and  may 
be  inflamed  in  an  atmosphere  rarified  sixty  times. 

It  may  be  set  on  fire  by  friction.  Rub  a  very  small  bit  between  two 
pieces  of  brown  paper,  or  of  wood  ;  the  phosphorus  will  inflame  and 
set  the  paper  on  fire  also. 

NATIVE  STATE  AND  PREPARATION.  Pure  phosphorus  does  not  exist  in 
nature,  but  some  of  its  acid  compounds  are  found  in  combination  with 
bases,  especially  in  the  form  of  phosphate  of  lime,  which  constitutes 
a  large  proportion  of  the  solid  matter  of  the  bones  of  animals. 


158  PHOSPHORUS. 

The  process  for  obtaining  phosphorus,  now  generally  adopted,  is,  to 
ignite  bones  in  an  open  fire,  till  they  become  quite  white,  so  as  to  de- 
stroy all  the  animal  matter  they  contain,  and  oxidize  the  carbon  pro- 
ceeding from  its  decomposition.  The  calcined  bones,  of  which  phos- 
phate of  lime  constitutes  nearly  four  fifths,  should  be  reduced  to  a 
tine  powder,  and  be  digested  for  a  day  or  two  with  half  their  weight 
of  concentrated  sulphuric  acid,  so  much  water  being  added  to  the  mix- 
ture as  to  give  it  the  consistence  of  a  thin  paste.  The  phosphate  of 
lime  is  decomposed  by  the  sulphuric  acid,  and  two  new  salts  are  gene- 
rated— the  sparingly  soluble  sulphate  and  a  soluble  biphosphate  of  lime. 
On  the  addition  of  boiling  water  the  biphosphate  is  dissolved,  and  may 
be  separated,  by  filtration,  from  the  sulphate  of  lime.  The  solution 
is  then  evaporated  to  the  thickness  of  syrup,  mixed  with  one-fourth 
its  weight  of  charcoal  in  powder,  and  heated  in  an  earthen  retort  well 
luted  with  clay.  The  beak  of  the  retort  is  put  into  water,  in  which 
the  phosphorus,  as  it  passes  over  in  the  form  of  vapour,  is  collected. 
When  first  obtained,  it  is  frequently  of  a  reddish-brown  colour,  owing 
to  the  presence  of  the  phosphuret  of  carbon,  which  is  generally  form- 
ed during  the  process.  It  may  be  purified  by  being  put  into  hot  water, 
and  pressed,  while  liquid,  through  chamois  leather  ;  or  the  purification 
may  be  rendered  still  more  complete  by  a  second  distillation. — Turner. 

ACTION  ON  THE  ANIMAL  ECONOMY.  Phosphorus  is  a  violent  and  gene- 
ral excitant.  In  small  doses  its  effects  are  very  soon  manifested,  but 
are  of  short  duration.  In  large  doses  it  occasions  death,  by  causing 
violent  inflammation.  Some  physicians  have  administered  it  in  solu- 
tion in  alcohol,  ether  and  the  oils  ;  others  have  recommended  it  in  the 
form  of  pills.  It  is  stated  by  Mr.  Murray,  that  if  phosphorus  be  allow- 
ed to  stand  in  water  for  some  time,  it  will  render  that  fluid  poisonous 
to  animals  that  drink  it. — Ann.  of  Phil.  xvi.  232. 

REFERENCES.  Lavoisier's  Elements  of  Chem.  Davy's  Elements  of  Chem. 
Aikiri's  Chemical  Diet,  containing  a  detailed  account  of  the  various  processes 
for  obtaining  Phosphorus,  and  of  its  action  upon  various  substances.  For 
the  action  of  Phosphorus  upon  various  mixtures  of  oxygen  and  other  gases 
see  Thenard,  i.  237.  Berzehus,  Trait,  de  Chim.  i.  254.  For  an  account  of 
the  poisonous  effects  of  Phosphorus,  fyc.  see  Beck's  Med.  Juris.  Dr.  Lobxtem 
on  Phosphorus. 

PHOSPHORUS    AND    OXYGEN. 

Oxide  of  Phosphorus  ? 

When  phosphorus  is  kept  under  water  for  some  time,  a  white  film 
forms  upon  its  surface,  which  some  have  regarded  as  an  oxide  of  phos- 
phorus. The  red  coloured  matter  which  remains  after  the  combustion 
of  phosphorus,  is  also  supposed  to  be  an  oxide.  But  chemists  have 
not  yet  succeeded  in  determining  the  nature  of  these  substances  in  a 
satisfactory  manner.  The  following  are  the  definite  compounds  of 
phosphorus  and  oxygen  now  generally  recognized,  viz  : 

P.         O. 

Hypophosphorous  Acid,    -  31-4 8=39-4 

Phosphorous  Acid, 15-7 12=27-7 

Phosphoric  Acid, 

Pyrophosphoric  Acid, 


PHOSPHORUS.  159 

Hypophosphorous  Add — Atom.  Num.  39-4 — Symb.  O+2P. 

This  acid  was  discovered  by  M.  Dulong,  in  1816,  and  may  be  form- 
ed by  the  action  of  water  upon  the  phosphuret  of  an  alkaline  metal, 
as  phosphuret  of  barium.  An  insoluble  precipitate  is  formed,  from 
which  the  liquid  is  to  be  separated  by  filtration.  To  this  solution  sul- 
phuric acid  is  carefully  added  so  long  as  any  precipitate  is  formed. 
The  sour  liquor  which  remains,  after  a  second  filtration,  is  to  be  con- 
centrated by  evaporation,  when  a  viscid,  uncrystallizable  acid  fluid 
will  be  obtained,  to  which  the  above  name  has  been  given. 

It  is  still  doubted,  by  some  chemists,  whether  it  may  not  be  a  triple 
compound  of  oxygen,  phosphorus  ,.and  hydrogen,  or  a  hydracid,  in 
which  case  its  proper  appellation  would  be  hydrophosphorous  acid. 

REFERENCES.  Dulong  in  Phil.  Mag.  xlviii.  271.  Sir  H.  Davy,  Phil. 
Trans.  1818,  and  Ann.  of  Phil.  xiii.  210.  Rose  on  the  Salts  of,  Ann.  de 
Chim.  etde  Phys.  July,  1828. 

Phosphorous  Acid. — Atom.  Num.   27.7  or  55*4 — Symb.  1J 
O+P. 

Discovered  by  Sir  H.  Davy,  in  examining  the  action  of  proto-chlo- 
ride  of  phosphorus  upon  water. 

PROPERTIES.  Phosphorous  acid  has  a  very  sour  taste,  and  smells 
somewhat  like  garlic  ;  reddens  litmus  powerfully  ;  is  decomposed  by 
heat,  yielding  the  same  products  as  the  hypophosphorous  acid  ;  unites 
with  bases  and  forms  salts,  which  are  termed  phosphites ;  in  solu- 
tion it  absorbs  oxygen  slowly  from  the  air,  and  is  converted  into 
phosphoric  acid  ;  has  a  great  tendency  to  unite  with  an  additional 
quantity  of  oxygen,  and  is,  therefore,  a  powerful  deoxidizing  agent, 
and  hence,  like  sulphurous  acid,  precipitates  mercury,  silver,  platinum 
and  gold,  from  their  saline  combinations  in  the  metallic  form  ;  by  ni- 
tric acid  it  is  converted  into  phosphoric  acid. 

PREPARATION.  This  acid  can  only  be  obtained  in  a  state  of  pu- 
rity by  subliming  phosphorus  through  powdered  corrosive  sublimate, 
contained  in  a  glass  tube.  A  liquid  comes  over  which  is  a  com- 
pound of  chlorine  and  phosphorus.  When  this  substance  is  put  into 
water,  a  peculiar  change  takes  place.  A  portion  of  water  is  decom- 
posed ;  its  hydrogen  unites  with  the  chlorine  and  forms  muriatic  acid  ; 
while  the  oxygen  combines  with  the  phosphorus  and  forms  phosphorous 
acid.  The  solution  is  then  evaporated  to  the  consistence  of  a  syrup, 
to  expel  the  muriatic  acid ;  and  the  residue,  which  is  the  hydrate  of 
phosphorous  acid,  becomes  a  crystalline  solid  on  cooling. 

Phosphoric  Add.— Atom.  Num.  35-7—  Symb.  2JO+P. 

J^seems  now  to  be  admitted  that  under  the  term  phosphoric  acid  two 
distinct  acids,  the  phosphoric  and  pyrophosphoric  have  heretofore  been 
usually  included.  These  compounds  are  of  great  interest  as  affording 
an  example  of  a  fact  but  recently  noticed,  viz  : — That  two  bodies  may 
consist  of  the  same  ingredients,  in  the  same  proportions,  and  yet  differ 
essentially  in  their  chemical  properties.  For  such  compounds,  of 
which  several  are  now  known,  Berzelius  has  proposed  the  general  ap- 


160  PHOSPHORUS. 

pellation  of  isomcric,  from  the  Greek  isomercs,  expressive  of  equality, 
in  the  ingredients. 

The  phosphoric  and  pyrophosphoric  acids  are  thus  distinguished 
from  each  other.  Phosphoric  acid  gives  a  yellow  salt  with  oxide  of  sil- 
ver, but  does  not  affect  albumen.  Pyrophosphoric  acid  yields  a  white 
salt  with  oxide  of  silver  and  precipitates  solution  of  albumen. 

These  acids  as  well  as  the  salts  which  they  form  are  easily  converted 
into  each  other  ;  and  during  these  changes  there  is  neither  gain  nor 
loss  of  either  of  their  elements.  Thus  by  a  red  heat  the  phosphoric 
acid  is  converted  into  the  pyrophosphoric  :  and  the  pyrophosphoric  is 
reconverted  into  the  phosphoric  in  the  course  of  a  few  days  by  cold  wa- 
ter, and  rapidly  by  hot  water  and  the  acids  : — and  the  salts  are  sub 
jected  to  similar  changes  by  the  application  of  the  same  agents. 

Phosphoric  acid. — This  acid  exists  only  in  solution,  for  the  applica- 
tion of  heat  necessary  to  expel  the  water  converts  it  into  the  pyro- 
phosphoric. It  has  an  intensely  sour  taste,  reddens  litmus,  and  neu- 
tralizes the  alkalies,  but  does  not  destroy  the  texture  of  the  skin. 

PREPARATION.  This  acid  is  readily  prepared  by  boiling  an  aqueous 
solution  of  pyrophosphoric  acid. 

Pyrophosphoric  acid. — Discovered  by  Mr.  Clarke  of  Glasgow  in  1827, 
[Brcicster 's  Jour.  vii.  298.]  and  distinguished  from  the  preceding  by 
the  characters  above  given. 

PREPARATION.  When  phosphorus  is  burned  in  a  dry  vessel  of  air 
or  oxygen  gas,  a  copious  white  smoke  appears,  which  soon  collects  in- 
to distinct  particles  and  falls  to  the  bottom  of  the  vessel  like  flakes  of 
snow.  This  substance  which  is  a  white,  bulky,  rather  tenacious  solid, 
is  an  hydrous  pyrophosphoric  acid.  On  exposure  to  the  air  it  rapidly 
absorbs  moisture,  with  which  it  constitutes  drops  of  a  densely  acid,  so- 
lution. When  kept  for  a  day  or  two,  it  becomes  phosphoric  acid. 

This  acid  maybe  also  obtained  by  the  cautious  addition  of  phosphor- 
us to  concentrated  nitric  acid,  evaporating  the  solution  thus  obtain- 
ed and  subjecting  it  to  a  red  heat.  But  this  process  requires  great 
care — and  a  cheaper  and  easier  method  consists,  in  mixing  biphosphate 
of  lime  obtained  from  bones  as  already  described,  with  carbonate  of  am- 
monia ;  boiling  the  mixture  for  a  few  minutes,  then  filtering,  and  eva- 
porating the  liquid  to  dryness — and  igniting  it  in  a  platinum  crucible. 

It  will  be  observed  that  in  the  processes  just  noticed,  phosphoric  acid 
exists  in  solution,  but  by  the  application  of  red  heat  it  becomes  pyro- 
phosphoric acid,  which  remains  in  the  crucible  united  with  water.  It 
concretes  on  cooling  into  a  kind  of  glass,  which  has  long  been  known 
under  the  name  of  Glacial  Phosphoric  Acid. 

REFERENCES.  The  papers  of  Sir  H.  Davy  already  quoted.  For  abstract? 
of  researches  on  the  combinations  of  Phosphorus  and  Oxygen,  by  Dulong, 
Berzelius,  Davy  and  Thomson,  see  Ann.  of  Phil.  ix.  xi.  a-nc/xiii.  ChaptaPa 
Chem.  iii.  78.  Johnston's  Report  on  Chemistry.  Also,  Tumer's  Chem.  4th 
London  ed. 

SALTS    OF    AMMONIA  AND  THE  ACIDS  CONTAINING    PHOSPPIORUS. 

Hypophosphite  of  Ammonia.     Very  soluble  both  in  water  and  in  al 
eohol.     Its  composition  has  not  been  ascertained. 

Phosphite  of  Ammonia. — A  very  soluble  salt,  which  is  with  difficulty 
brought  to  crystallize. 


PHOSPHORUS.  161 

Phosphate  of  Ammonia. — Crystallizes  in  low  four-sided  pyramids 
with  square  bases  ;  soluble  in  twice  its  weight  of  water  at  55°  F. ; 
when  heated  it  fuses,  swells,  and  if  the  heat  be  strongly  urged, 
loses  its  alkaline  base,  the  phosphoric  acid  being  left  in  the  glacial 
form. 

This  salt  may  be  formed  by  saturating  phosphoric  acid  with  am' 
monia. 

Besides  the  above,  which  is  a  neutral  salt,  there  is  also  a  &£• 
phosphate. 

PHOSPHORUS  AND  CHLORINE. 

There  are  two  compounds  of  chlorine  and  phosphorus,  viz.  the  Pro- 
tochloride  and  the  Perchloride. 

Proto chloride    of  Phosphorus — Atom.    Num.  63'87 — Symb. 
1  JC.1+P—  %  gr.  1-45  water=l. 

PROPERTIES.  A  transparent  and  colourless  liquid,  it  does  not  affect 
the  colour  of  litmus  paper,  but  the  fumes,  which  it  gives  off  in  abun- 
dance, are  acid,  owing  to  contact  with  the  moisture  of  the  atmos- 
phere ;  acts  energetically  upon  water,  the  hydrogen  combining  with 
the  chlorine,  forming  muriatic  acid,  and  the  oxygen  with  the  phospho- 
rus, by  which  the  phosphoric  acid  is  produced,  as  before  described,  (p. 
159);  in  which  process  the  muriatic  acid  is  driven  off  by  heat,  and 
pure  phosphorus  acid  remains. 

PREPARATION.  This  compound  may  be  made  either  by  heating  th  e 
perchloride  with  phosphorus,  or  by  passing  the  vapour  of  phosphorous 
over  corrosive  sublimate,  heated  in  a  glass  tube. 

Perchloride  of  Phosphorus—Atom.  Num.  104*32— Symb.  2% 

Cl+P. 

When  phosphorus  is  introduced  into  chlorine,  it  inflames  spontane- 
ously, and  burns  with  a  pale  flame.  The  product  is  a  white  solid, 
which  condenses  upon  the  sides  of  the  vessel. 

This  solid  compound,  which  is  the  perchloride  of  phosphorus,  is  vo- 
latile at  a  temperature  below  212°  ;  but  may  be  fused  under  pressure, 
and  crystallizes  in  cooling.  It  acts  with  violence  upon  water,  forming 
with  its  elements  phosphoric  and  muriatic  acids.  When  transmitted 
with  oxygen  gas  through  a  red-hot  porcelain  tube,  chlorine  is  evolved, 
and  phosphoric  acid  is  formed,  showing  that  at  high  temperatures,  the 
affinity  of  oxygen  for  phosphorus,  is  stronger  than  that  of  chlorine. — 
Henry,  i.  40  L. 

REFERENCES.  Davy  in  Phil.  Trans,  for  1812,  under  the  names  of  "Phos~ 
phorane"  and  "  Phosphorana"  Also,  his  Elements  of  Chem.  Phil.  Gay 
Lussac  and  Thenard,  Recherches,  Phys.  Chini.  ii. 

PHOSPHORUS  AND    BROMINE. 

When  bromine  and  phosphorus  are  brought  into  contact  in  a  flask 
filled  with  carbonic  acid  gas,  they  act  suddenly  on  each  other  with  the 


162  PHOSPHORUS. 

evolution  of  heat  and  light,  and  two  compounds  are  generated  ;  one  a 
crystalline  solid  which  is  sublimed  and  collects  in  the  upper  part  of  the 
flask,  and  the  other  a  fluid,  which  remains  at  the  bottom.  The  latter 
is  regarded  by  M.  Balard  as  a  Protobromide,  and  the  former  as  a  Dcu- 
tobromide  of  Phosphorus. 

PHOSPHORUS    AND    IODINE. 

Iodine  and  phosphorous  combine  readily  in  the  cold,  evolving  so 
much  caloric  as  to  kindle  the  phosphorus,  if  the  experiment  is  made 
in  the  open  air  ;  but  in  close  vessels  no  light  appears.  The  combina- 
tion takes  place  in  several  proportions,  which  have  not  been  determined. 
Its  most  interesting  property  is  that  of  decomposing  water,  with  the 
formation  of  hydriodic  and  phosphoric  acids. 

REFERENCES.  Davy,  in  Phil.  Trans.  1814.  Gay  Lussac,  in  Ann.  de 
Chim.  xci.  9. 

PHOSPHORUS    AND    HYDROGEN. 

Of  all  the  compounds  to  which  chemists  have  directed  their  atten- 
tion, none  are  perhaps  less  perfectly  understood  than  those  of  phos- 
phorus and  hydrogen.  All  writers  on  the  subject,  with  the  exception 
of  Mr.  Dalton,  who  contends  that  there  is  only  one  species  of  phos- 
phuretted  hydrogen,  admit  the  existence  of  two  at  least.  To  these 
Dr.  Thomson  has  added  a  third,  which  does  not,  however,  appear  yet 
to  have  been  examined  by  other  chemists.  Berzelius  recognizes  four 
compounds  of  phosphorus  and  hydrogen,  containing  different  propor- 
tions of  hydrogen  united  to  the  same  of  phosphorus. — Traite  de  Chim. 
i.  263. 

Hydruret  of  Phosphor  us*— Atom.  Num.  167  ?—  Symb.U+P  ? 

SYN.  Perphosphuretted  Hydrogen  Gas.  Phosphure  Trihydrique. — 
Berzelius. 

Discovered  in  the  year  1783,  by  Gengembre,  and  since  particular- 
ly examined  by  Mr.  Dalton,  Dr.  Thomson,  M.  Dumas  and  Prof.  H. 
Rose. 

PROPERTIES.  A  colourless  gas,  possessing  a  highly  offensive  smell, 
resembling  that  of  garlic,  and  a  bitter  taste  ;  it  is  very  slightly  soluble 
in  water  ;  does  not  support  flame  or  respiration  ;  inflames  spontane- 
ously when  mixed  with  air  or  oxygen  gas  ;  its  specific  gravity  is  !•] 
according  to  Dalton,  0-9027  according  to  Dr.  Thomson,  and  1-761  ac- 
cording to  Dumas. 

It  is  slightly  absorbed  by  water. — Recently  boiled  water,  according  to 
Dalton,  absorbs  fully  one-eighth  of  its  bulk  of  this  gas,  most  of  which 
is  again  expelled  by  boiling  or  agitation  with  other  gases  ;  but  Dr. 

*  According  to  Prof.  H.  Rose,  this  gas  and  the  next  have  the  same  com- 
position and  specific  gravity  ;  both  consisting  of  one  volume  phosphorus 
vapour-j-three  volumes  hydrogen,  condensed  into  two  volumes.  And  this 
view  is  said  to  be  confirmed  by  a  fact  noticed  by  Serullas. — Johnstons  Re- 
port  on  Chemistry. 


PHOSPHORUS.  163 

Thomson  states  that  water  takes  up  only  about  five  per  cent  of  its 
volume.  The  aqueous  solution  does  not  redden  litmus  paper,  nor  does 
the  gas  itself  possess  any  of  the  properties  of  acids.  The  gas  is  free- 
ly and  completely  absorbed  by  a  solution  of  sulphate  of  copper  and 
chloride  of  lime,  by  which  means  its  purity  may  be  ascertained,  and 
the  presence  of  hydrogen  detected. 

When  this  gas  is  allowed  to  stand  for  a  few  days  over  water,  it  de- 
posits part  of  its  phosphorus  without  change  of  volume,  and  ceases  to 
be  spontaneously  combustible  when  mixed  with  atmospheric  air.  Ac- 
cording to  Dr.  Thomson,  it  parts  with  l-4th  of  its  phosphorus  under 
these  circumstances,  and  a  peculiar  gas,  which  he  has  called  Subphos- 
phuretted  Hydrogen,  is  generated  ;  but  M.  Dumas  maintains  that  l-3d 
of  the  phosphorus  is  deposited,  and  that  the  new  gas  is  identical  with 
protophosphuretted  hydrogen,  (bihydruret  of  phosphorus.) 

It  inflames  spontaneously  when  admitted  into  air  or  oxygen  gas. — 
This  is  the  most  remarkable  property  of  this  gas,  and  by  means  of 
which  it  is  distinguished  from  all  other  gases.  If  the  beak  of  the  re- 
tort from  which  it  issues,  is  plunged  under  water,  so  that  successive 
bubbles  of  the  gas  may  arise  through  the  liquid,  a  very  beautiful  ap- 
pearance takc»s  place.  Each  bubble  on  reaching  the  surface  of  the  wa- 
ter bursts  into  a  flame,  and  forms  a  ring  of  dense  white  smoke,  which 
enlarges  as  it  ascends,  and  retains  its  shape,  if  the  air  is  tranquil,  until 
it  disappears.  This  takes  place  even  at  the  temperature  of  freezing 
mercury,  as  observed  by  Rose.  [Ann.  de  Chim.  etde  Ph.  Feb.  and  Jug. 
1827.]  If  received  into  a  vessel  of  oxygen  gas,  the  entrance  of  each 
bubble  is  instantly  followed  by  a  strong  concussion,  and  a  flash  of 
white  light  of  extreme  intensity.  Hence  this  experiment  should  be 
performed  with  some  caution. — Silliman's  Jour.  vi.  187. 

PREPARATION.  Hydruret  of  phosphorus  may  be  prepared  in  several 
ways  : 

1.  By  throwing  into  water  the  phosphuret  of  any  metal,  which  me- 
tal per  se  will  decompose  water,  as  phosphuret  of  potassium,  sodium, 
calcium,  &c. 

2.  From  a  combination  of  phosphorus  and  the  oxides  of  these  me- 
tals, as  potash,  soda,  lime,  &c.,  by  the  application  of  a  sufficient  heat 
to  enable  the  phosphorus  to  effect  a  decomposition  of  the'se  oxides. 

3.  By  the  addition  of  a  dilute  acid  to  phosphorus  and  those  metals 
which  are  usually  employed  in  procuring  hydrogen  gas,  as  iron,  zinc, 
&c. — Sillimans  Jour.  xii.  294. 

Bihydruret  of  Phosphorus* — Atom.  Numb.I7'7?  Symb. 
2H+P? 

SYN.  Protophosphuretted  Hydrogen,  Dumas.  Hydrophosphoric  Gas, 
Davy.  Phosphure  Bihydrique,  Berzelius. 

Discovered  by  Sir  H.  Davy  in  1812. 


*  This  is  now  (bought  to  be  a  compound  of  3  hydrogen-j-1  phosphorus,  and 
to  be  analogous  in  its  composition  to  Ammonia.  And  one  of  the  most  curious 
facts  lately  made  out  with  regard  to  it,  is  that  it  agrees  also  with  ammonia  in 
its  power  of  forming1  crystallizable  compounds  with  the  hydrogen  acids. — 
These  compounds  are,  moreover,  similar  in  constitution  and  in  crystalline 
form  to  the  analogous  salts  of  ammonia. — Johnston's  Report  on  Chemistry. 


164  CARBON. 

PROPERTIES.  A  colourless  gas,  of  a  disagreeable  odour,  though  less 
fetid  than  the  foregoing  ;  is  absorbed  by  water  ;  does  not  take  fire 
spontaneously  when  mixed  with  air  or  oxygen  gas  at  common  tem- 
peratures, but  the  mixture  detonates  with  the  electric  spark,  or  when 
heated  to  300°  F.;  admitted  into  a  vessel  of  chlorine,  it  inflames  in- 
stantly and  emits  a  white  light,  a  property  which  it  possesses  in  com- 
mon with  perphosphuretted  hydrogen  ;  its  specific  gravity  is  estima- 
ted by  Dr.  Thomson  at  0-9722  ;  but  M.  Dumas  found  it  to  be  1-214. 

PREPARATION.  This  gas  was  prepared  by  Sir  H.  Davy  by  exposing 
to  heat  in  a  retort  the  solid  hydrate  of  phosphorous  acid  ;  and  the  same 
gas  is  evolved  by  treating  the  hydrous  hypophosphorous  acid  in  the 
same  manner.  It  is  also  formed,  according  to  Dumas,  by  the  action 
of  concentrated  muriatic  acid  on  phosphuret  of  lime  ;  and  likewise 
by  the  spontaneous  decomposition  of  perphosphuretted  hydrogen 
gas. 

REFERENCES.  Dalto7t's  New  Syst.  of  Chem.  Phil.  Sir  H.  Davy  in  PhiL 
Trans.  1312,  containing  the  first  particular  examination  of  Bihydruret  of 
Phosphorus.  Thomson's  Experiments  on  Phos.  Hyd.  Gas.  Ann.  of  Phil. 
•viii.  87.  The  Essays  of  Dumas  and  of  Rose,  Ann.  do  Ch.  et  de  Phys.  xxxi. 
xxxiv.  Henry's  Chem.  ii.  692. 

PHOSPHORUS    AND    SULPHUR. 

Sulphur  et  of  Phosphorus. 

When  sulphur  is  brought  into  contact  with  fused  phosphorus,  they 
unite  readily,  but  in  proportions  which  have  not  been  precisely  de- 
termined ;  and  they  frequently  react  on  each  other  with  such  violence 
as  to  cause  an  explosion.  These  substances  may  also  be  made  to  com- 
bine by  agitation  under  water,  the  temperature  of  which  should  not 
exceed  160°  F.  The  compound  has  a  reddish  brown  colour,  and  is 
fluid  at  about  40°  F.  It  is  more  fusible  than  phosphorus,  and  is  high- 
ly combustible. — BrandesJour.  iv.  361. 

REFERENCES.  Pelletier,  Ann.  de  Chitn.  iv.  10.  Accum  and  Briggs* 
Nicholson's  Jour.  vi.  and  vii. 

SECTION  V. 

CARBON. 
Atom.  Num.  6—Symb.  C—Sp.  gr.  3  52  water=l. 

Perfectly  pure  carbon  is  rare  in  nature,  and  cannot  be  prepared  by 
arl .  1  only  occurs  in  a  precious  stone  called  the  diamond. 

The  diamond  is  found  in  many  parts  of  the  East  Indies,  especially  in 
tli3  provinces  of  Golconda  and  Visapour,  in  Bengal,  and  in  the  island  of 
Borneo.  About  the  year  1720,  diamonds  were  first  found  in  the  district 
of  Serra  Dofrio,  in  Brazil.  They  always  occur  in  detached  crystals  in 
alluvial  soil.  The  primitive  form  of  the  diamond  is  the  regular  octahe- 
dron, each  triangular  facet  of  which  is  sometimes  replaced  by  six  se- 
condary triangles,  bounded  by  curved  lines  ;  so  that  the  crystal  be- 
comes spheroidal,  and  presents  48  facets.  Diamonds  with  12  and  24 


CARBON.  165 

facets  are  not  uncommon.  [Jameson  s  Mineralogy."]  The  diamond  has 
been  found  nearly  of  all  colours  ;  those  which  are  colourless  are  most 
esteemed  ;  then  those  of  a  decided  red,  blue  or  green  tint.  Black  dia- 
monds are  extremely  rare.  Those  which  are  slightly  brown  or  tinged 
with  other  colours,  are  least  valuable.  It  is  the  hardest  body  in  nature. 
The  best  tempered  steel  does  not  scratch  it.  It  refracts  light  pow- 
erfully, and  hence  Newton  was  led  to  conjecture  its  combustibil- 
ity ;  a  conjecture  which  was  rendered  probable  by  the  experiments 
of  the  Florentine  academicians  in  1694,  and  which  was  subsequently 
confirmed  by  several  philosophers.  The  products  of  its  combustion 
were  first  examined  by  Lavoisier  in  177*2,  arid  subsequently  with  more 
precision  by  Guy  ton  Morveau,  in  1785.  [Ann.  de  C/iim.  xxxi.]  In 
1797,  Mr.  Tennant  demonstrated  the  important  fact,  that  when  equal 
weights  of  diamond  and  pure  charcoal  were  submitted  to  the  action  of 
red  hot  nitre,  the  results  were  in  both  cases  the  same  ;  and  in  1807,  the 
combustion  of  the  diamond  in  pure  oxygen,  was  found  by  Messrs.  Al- 
len and  Pepys  to  be  attended  with  precisely  the  same  results  as  the 
combustion  of  pure  charcoal.  Hence  the  inevitable  inference  that 
charcoal  and  the  diamond  are  substances  similar  in  their  chemical  na- 
ture ;  differing  only  in  mechanical  texture.  [Phil.  Trans.  1807.]  This 
view  was  confirmed  by  Sir  H.  Davy,  [Phil.  Trans.  1814,]  who  com- 
pared the  product  of  the  combustion  of  the  diamond  with  that  derived 
from  different  kinds  of  charcoal.  Further  proof  of  the  identity  of 
charcoal  and  the  diamond,  is  furnished  by  the  fact  that  the  diamond 
converts  iron  into  steel,  under  circumstances  quite  free  from  all  sources 
of  fallacy.—  Phil.  Trans.  1815,  371. 

Next  to  the  diamond  the  most  remarkable  and  purest  forms  of  car- 
bon, are 

1.  Graphite  or  Black  Lead. — A  mineral  of  a  lead  grey  colour,   from 
which  common  crayons  are  manufactured,  found  in  beds  in  mountains 
belonging  to  primitive  formations.     As  it  generally  leaves   after  its 
combustion  a  cinder  which  contains  much  iron,  it  was  supposed  to  be 
a  compound  of  carbon  with  about  5  per  cent,  of  this  metal.     But  more 
recent  researches,  especially  those  of  Karsten,   have  proved  beyond  a 
doubt  that  it  is  a  peculiar  form  of  carbon,  and  that  the  foreign  sub- 
stances which  accompany  it,  are  merely  accidental.     The  graphite  of 
Barreros  is  Brazil,  leaves  scarcely  a  trace  of  residuum  when  it  is  burn- 
ed.— Berzelius,    i.  313. 

2.  Anthracite. — Another  species  of  fossil  carbon,  differing  from  coal 
in  that,  when  sufficiently  heated,   it  burns  without  flame,  odour  or 
smoke. 

3.  Cook. — A  name  applied  in  England  to  a  carbonaceous  mass  of  an 
iron  black  colour,  and  semi-metallic  lustre,  which  remains  after  coal 
has  been  deprived,  by  means  of  heat,  of  ail  the  volatile  parts  which  it 
contains. 

4.  Charcoal. — A  substance  obtained  by  burying  in  sand,  in  a  crucible, 
pieces  of  oak,  willow,  hazel,  or  other  woods  deprived  of  bark,  and  ex- 
posing them  covered  to  the  strongest  heat  of  a  wind  furnace.     For 
purposes  of  accuracy,  charcoal  must  be  used  when  recently  prepared, 
and  before  it  has  had  time  to  become  cold  ;  or  if  it  cannnot  be  had 
fresh  made,  it  must  be  heated  again  to  redness  under  sand  in  a  cruci- 
ble. 

Different  kinds  of  wood  furnish  variable  quantities  of  charcoal ;  ma- 
hogany, oak,  fir  and  box  are  the  most  highly  esteemed.  —  See  Allen  and 
Fepys,  Phil.  Trans.  1807. 


166  CARBON. 

In  the  large  way,  charcoal  is  often  prepared  by  the  distillation  of 
wood  in  cast-iron  cylinders.  The  loppings  of  young  trees,  commonly 
called  crop-wood,  are  generally  employed  ;  and,  besides  the  charcoal, 
liquid  products  of  value  are  collected,  especially  an  impure  vinegar, 
known  under  the  name  of  pyroligneous  acid. — Parkes'  Chem.  Essays,  ii. 
271. 

The  more  common  method,  in  this  country  especially,  is  to  form  the 
wood  into  a  conical  pile,  which  being  covered  with  earth  or  clay,  is 
suffered  to  burn  with  a  limited  access  of  atmospheric  air,  by  which  its 
complete  combustion,  or  reduction  to  ashes,  is  prevented. 

5.  Lampblack. — This  is  obtained  chiefly  by  turpentine  manufactur- 
ers, from  refuse  resin,  which  is  burned  in  a  furnace  so  constructed  that 
the  dense  smoke  arising  from  it  may  pass  into  chambers  hung  with 
sacking,  where  the  soot  is  deposited,   and  is  swept  off  from  time  to 
time,  and  sold  without  further  preparation.     When  heated  red  hot  in 
a  close  vessel,  it  forms  a  very  pure  carbon.     Lampblack  may  also  be 
obtained  by  passing  the  vapour  of  the  oil  of  turpentine,  or  of  spirit  of 
wine,  through  a  red  hot  tube  ;  or  by  the  combustion  of  camphor,  which 
forms  the  basis  of  a  very  fine  black  paint. 

6.  JUnimal  charcoal. — This  is  obtained  by  subjecting  bones  to  a  red 
heat  in  a  covered  crucible.     It  is  a  black  mass,  of  a  metallic  lustre, 
consisting  of  charcoal  mixed  with  the  earthy  matters  of  the  bone. — 
When  reduced  to  powder,  it  occurs  in  commerce  under  the  name  of 
Ivory  black. 

7.  A  new  and  curious  form  of  carbon  has  been  described  by   Dr. 
Colquhoun  of  Glasgow.     When  coal  gas  is  passed  over  red  hot  iron, 
in  Mr.  Mackintosh's  process  for  converting  iron  into  steel,  this  variety 
of  carbon  is  deposited  in  long  capillary  threads,  very  fine,  brittle,  per- 
fectly black,  and  having  considerable  lustre.     In  its  external  appear- 
ance, though  this  is  the  most  perfect,   many  shades  of  difference  oc- 
cur.— Jinn,  of  Phil,  xxviii.  1. 

PROPERTIES  OF  CHARCOAL.  A  black,  insoluble,  inodorous,  insipid, 
brittle  substance  ;  an  excellent  conductor  of  electricity,  but  a  bad  con- 
ductor of  heat  ;*  unchanged  by  the  combined  action  of  air  and  moist- 
ure at  common  temperatures  ;  infusible,  and  easily  combustible  in 
oxygen  gas  ;  is  capable  of  destroying  the  smell  and  taste  of  a  variety 
of  vegetable  and  animal  substances. — Lowitz,  Crells  Annals,  ii.  165. 

Charcoal  has  the  property  of  absorbing  gases  icithout  alteration. — 
Fill  a  jar  with  common  air,  or  any  other  gas,  and  place  it  over  dry 
mercury  ;  take  a  piece  of  charcoal,  red-hot  from  the  fire,  and  plunge 
it  in  the  mercury  of  the  bath  ;  when  cold,  let  it  be  passed  into  the  ves- 
sel of  gas,  without  bringing  it  into  contact  with  the  atmosphere.  A 
considerable  diminution  of  the  gas  will  be  effected  ;  and  in  24  or  36 
hours  its  absorption  will  be  completed. 

This  property  of  charcoal  has  been  made  the  subject  of  valuable  sets 
of  experiments  by  Saussure  and  Count  Morozzo.  [Ann.  of  Phil. 

*  Dr.  Thomson  states,  on  the  authority  of  Cheuvreusse,  (hat  charcoal  form- 
ed under  a  red  heat  is  a  non-conductor  of  electricity,  and  cannot  be  employed 
as  one  of  the  elements  of  the  Voltaic  battery.  It  is  also  a  bad  conductor  of 
heat.  Charcoal  formed  by  a  red  heat  is  an  excellent  conductor  of  electricity 
and  of  heat,  and  is  not  nearly  so  combustible  as  the  first  species. — Inorganic 
Chem.  i.  149. 


CARBON.  167 

vi.  241.  Henry's  Chem.  i.  361.]  The  absorption  appears  to  be  a  mere 
mechanical  effect  ;  for  even  those  gases  which  have  an  affinity  for 
charcoal,  (as  hydrogen  and  oxygen,)  are  given  out  unchanged  at  the 
heat  of  boiling  water. — Thenard,  i.  219. 

It  resists  the  putrefaction  of  animal  substances. — Meat  which  has  be- 
come tainted  may  even  have  its  sweetness  restored  by  rubbing  with 
charcoal,  and  may  be  preserved  sweet  by  being  buried  in  its  powder. 
It  also  produces  the  remarkable  effect  of  destroying  the  colour  and 
smell  of  many  animal  and  vegetable  substances.  Common  vinegar, 
by  being  boiled  with  it,  becomes  perfectly  colourless  ;  and  red  wines, 
rum  or  brandy  may  be  bleached  by  filtration  through  it.  It  is  largely 
employed,  for  this  purpose,  in  the  process  of  sugar  refining,  and  for 
preparing  colourless  crystals  of  citric  acid  and  other  vegetable  pro- 
ductions. Charcoal,  prepared  by  calcining  animal  substances  in  close 
vessels,  has  been  found  most  efficacious  for  these  purposes. — Ann.  de 
Chim.  Ixxix.  80.  Brandes  Jour.  iv.  367.  See  also  Graham's  paper  on 
the  effects  of  Animal  Charcoal  on  solutions.  Brandes  Jour.  N.  S.  vii. 
120. 

It  is  a  very  slow  conductor  of  heat. — The  experiments  of  Guyton 
Morveau  have  determined,  that  caloric  is  conveyed  through  charcoal 
more  slowly  than  through  sand,  in  the  proportion  of  three  to  two. 
Hence  powdered  charcoal  may  be  advantageously  employed  to  sur- 
round substances  which  are  to  be  kept  cool  in  a  warm  atmosphere  ; 
and  also  to  confine  the  caloric  of  heated  bodies.  It  affords,  however, 
an  easy  transmission  to  the  electric  fluid. 

Spontaneous  inflammation  of  powdered  charcoal. — It  has  long  been 
known  that  charcoal  in  a  state  of  fine  powder,  often  inflames  sponta- 
neously. The  subject  has  recently  been  examined  by  Col.  Aubert  of 
the  French  artillery,  and  others,  arid  some  interesting  facts  have  been 
made  known.  It  appears  that  spontaneous  combustion  ensues  in  al- 
most all  cases  when  20  or  30  cwt.  of  charcoal  in  a  state  of  minute  di- 
vision, are  put  together  in  a  heap  and  left  undisturbed.  Col.  Aubert 
ascribes  the  combustion  in  such  cases  to  the  absorption  of  air  which 
occasions  a  disengagement  of  heat ;  but  it  is  most  probably  owing,  as 
is  suggested  by  Mr.  Davies,  to  the  action  of  air  and  moisture  on  the 
minute  portions  of  potassium  which  charcoal  contains.  Perhaps  this 
may  also  account,  at  least  in  some  degree,  for  the  singular  power 
of  absorption  which  charcoal  possesses. — See  Land,  and  Edin.  Phil. 
Mag.  iii.  1  and  89. 

REFERENCES.  Tennaut  on  the  nature  of  the  Diamond,  Phil.  Trans.  1797. 
Repert.  of  Arts,  1st  ser.  viii.  113.  Mawe's  Treaties  on  Diamonds,  fyc. 
Cheuvreusse's  P hy si co-  Chemical  Researches  on  Charcoal,  Ann  de  Chim. 
Aug.  1825,  and  in  Repert.  of  Patent  Inventions,  ii.  387.  Parkes*  Chem. 
Essays,  ii.  249,  containing  an  account  of  the  various  forms  of  Carbon,  me- 
thods of  preparing  Charcoal,  SfC.  Spc.  Doolittle^s  new  method  of  making 
Charcoal.  Killimari's  Jour.  xvii.  395. 


CARBON   AND    OXYGEN. 

There  are  two  compounds  of  these  substances,  the  one  known  un- 
der the  name  of  Carbonic  Oxide,  the  other  of  Carbonic  Acid, 


168  CARBON. 

Carbonic    Oxide. — Atom.  Num.   14 — Symb.Q-\-C — Sp.gr. 
O-9721  air-1. 

SYN.     Gaseous  Oxide  of  Carbon. 

This  gas  appears  to  have  been  first  obtained  by  Dr.  Priestley  ;  but 
its  true  nature  was  first  made  known  by  Mr.  Cruickshanks  of  Wool- 
wich, in  1802. — [Nicholson's  Jour.  4to.  v.J  and  it  was  afterwards  more 
particularly  examined  by  M.  M.  Clement  and  Desormes. — Ann.  de 
Chim.  xxxix.  26. 

PROPERTIES.  A  gaseous  body,  of  an  offensive  smell,  colourless  and 
insipid  ;  very  sparingly  soluble  in  water,  and  it  does  not  in  any  way  af- 
fect the  colour  of  blue  vegetable  infusions  ;  it  is  inflammable,  and  when 
set  on  fire  as  it  issues  from  the  orifice  of  a  small  pipe,  burns  with  a  fee- 
ble blue  flame,  but  a  lighted  taper  plunged  into  ajar  full  of  the  gas  is  in- 
stantly extinguished  ;  is  noxious  to  animal  life,  when  received  into  the 
lungs,  and  when  respired  for  a  few  minutes  produces  giddiness  and 
fainting.— Phil.  Mag.  xliii.  367.  .Beck's  Med.  Juris.  305. 

When  a  mixture  of  carbonic  oxide  and  an  equal  bulk  of  hydrogen, 
is  passed  through  an  ignited  tube,  the  tube  becomes  lined  with  char- 
coal. At  this  temperature,  the  hydrogen  attracts  oxygen  more  strong- 
ly than  it  is  retained  by  the  charcoal,  and  water  is  formed.  When 
mixed  with  half  its  volume  of  oxygen  gas,  and  the  mixture  fired  over 
mercury,  in  a  detonating  tube,  150  measures  of  the  mixture  will  be 
converted  into  100  measures  of  carbonic  acid,  if  the  gases  employed  be 
perfectly  pure.  It  was  found,  also,  by  Gay  Lussac,  that  carbonic 
oxide  is  decomposed  by  the  action  of  potassium,  which  combines  with 
the  oxygen,  and  precipitates  charcoal ;  and  Dobereiner  by  bringing  it 
into  contact  with  sulphuretted  oxide  of  platinum,  converted  it  into 
half  its  volume  of  carbonic  acid. 

PREPARATION.     This  gas  may  be  prepared  in  either  of  the  following 

ways. 

1.  By  introducing  into  a  gun  barrel  a  mixture  of  equal  parts  of  well 
dried  carbonate  of  baryta,  or  of  lime,  (common  chalk,)  and  charcoal 
pulverized,  or  of  chalk  and  dry  zinc  or  iron  filings,  and  exposing  them 
to  a  strong  heat.     In  this  case  the  charcoal,  iron  or  zinc  filings  com- 
bine with  one  proportion  of  oxygen  in  the  carbonic  acid  of  the  carbon- 
ate of  lime  or  baryta,  and  convert  it  into  carbonic  oxide. 

2.  By  transmitting  carbonic  acid  gas  over  charcoal  ignited  in  a  por- 
celain tube,  the  acid  gas  combines  with  an  additional  dose  of  charcoal, 
loses  its  acid  properties,  and  is  converted  into  a  double  volume  of  car- 
bonic oxide. 

3.  By  mixing  binoxalate  of  potassa,  [salt  of  sorrel,]  with  five  or  six 
times  it  weight  of  concentrated  sulphuric  acid,  and  heating  the  mix- 
ture in  a  glass  bottle.     [Dumas,  Ann.  dc  Chim.etde  Phys.  xxxiii,  110.] 
The  evolved  gas,  after  removing  the  carbonic  acid  by  washing  in  lime 
water  or  liquid  potassa,  is  pure  carbonic  oxide.     This  washing  is,  in- 
deed, necessary,  from  whatever  source  the  gas  may  have  been  ob- 
tained. 

To  understand  the  theory  of  this  process,  we  should  remark  that 
oxalic  acid  is  a  compound  of  equal  measures  of  carbonic  acid  and  car- 
bonic oxide,  or  at  least  its  elements  are  in  the  proportion  to  form  these 
gases  ;  and  that  it  cannot  exist  unless  in  combination  with  water,  or 


CARBON.  169 

some  other  substance.  Now  the  sulphuric  acid  unites  with  both  the 
potassa  and  water  of  the  binoxalate.  and  the  oxalic  acid  being  thus  set 
free,  is  instantly  decomposed.  Oxalic  acid  may  be  substituted  in  this 
process  for  the  binoxalate  of  potassa. 

Carbonic  Add— Atom.  Num.  22—Symb.  2O+C— Sp.  gr. 
1-5277  air=L 

This  acid  was  discovered  by  Dr.  Black,  in  1757,  and  described  by 
him,  in  his  inaugural  dissertation,  de  Magnesia  Alba,  under  the  name  of 
Fixed  Mr.  Its  nature  was  first  demonstrated  synthetically  by  La- 
voisier, and  analytically  by  Mr.  Tennant. 

PROPERTIES.  A  colourless,  inodorous,  elastic  fluid,  possessing  all 
the  physical  properties  of  the  gases  in  a  high  degree,  and  requiring  a 
pressure  of  thirty-six  atmospheres  to  condense  it  into  a  liquid ;  is 
rather  more  than  by  one  half  heavier  than  atmospheric  air  ;  it  is  per- 
fectly uninflammable,  and  instantly  extinguishes  flame  ;  is  speedily 
fatal  to  animal  life,  even  when  in  moderate  proportion  ;  is  absorbed  by 
water  to  the  amount  of  its  own  bulk,  under  common  pressure  and  tem- 
perature, but  the  quantity  taken  up  may  be  greatly  increased  by  in- 
creasing the  pressure;  the  solution  has  an  agreeable  subacid  taste, 
and  reddens  paper  stained  with  the  blue  colour  of  litmus. 

It  extinguishes  flame. — Set  a  vessel  filled  with  the  gas,  with  its  mouth 
upwards,  and  let  down  alighted  candle.  The  candle  will  be  instantly 
extinguished.  The  combustion,  in  this  case,  does  not  cease  from  the 
want  of  oxygen  only,  as  appears  from  the  fact  that  a  candle  cannot 
burn  in  a  gaseous  mixture  composed  of  four  measures  of  atmospheric 
air  and  one  of  carbonic  acid.  It  appears  therefore  to  exert  a  positive 
influence  in  checking  combustion. 

It  is  heavier  than  atmospheric  air. — From  the  great  specific  gravity  of 
carbonic  acid,  it  will  remain  for  some  time  at  the  bottom  of  a  jar  with 
its  mouth  turned  upwards  ;  and  may  be  poured  from  one  such  vessel 
into  another  like  water.  It  is  an  amusing  experiment  to  place  a  light- 
ed taper  in  the  bottom  of  the  jar,  as  it  will  be  instantly  extinguished 
by  pouring  the  gas  upon  it  like  a  liquid. 

It  is  owing  to  the  same  property  that  carbonic  acid  gas  is  often 
found  at  the  bottom  of  grottoes,  of  deep  wells  and  of  mines,  the  up- 
per part  of  which  is  entirely  free  from  it,  and  which,  from  its  injurious 
effects,  is  called  by  the  miners,  choak  damp.  Hence  the  precautions, 
used  by  the  sinkers  of  wells,  of  letting  down  a  candle  before  they  ven- 
ture to  descend  in  person.* 

It  is  absorbed  by  water. — This  may  be  easily  demonstrated,  by  agitat- 
ing the  gas  with  that  liquid,  or  by  leaving  a  jar  full  of  it  inverted 
over  water.  In  the  first  case  the  gas  disappears  in  the  cburse  of  a 
minute  ;  in  the  latter  it  is  absorbed  gradually.  If  more  pressure  be  ap- 
plied, the  amount  absorbed  by  water  is  greatly  increased.  Dr.  Hen- 
ry has  ascertained,  from  an  extensive  series  of  experiments,  that 
the  quantity  of  gas  absorbed  by  water  is  directly  as  the  pressure  ;  that 

*  This  can  generally  be  depended  on  ;  but  Dr.  Christison  states  that  some 
instances  have  been  known  of  the  atmosphere  being  sufficiently  loaded  with 
carbonic  acid  to  produce  insensibility,  and  yet  not  so  impure  as  to  extinguish 
a  burning  candle. —  Treatise  on  Poisons,  2o?  ed.  707. 


170  CARBON. 

is,  water  dissolves  twice  its  volume,  when  the  pressure  is  double,  and 
three  times  its  volume,  when  the  pressure  is  treble,  &c.  [Henry's 
Chem.  i.  372.  Phil.  Trans.  1803.]  It  is  by  the  strong  compression  of 
a  forcing  pump  that  the  common  soda  water  is  so  highly  charged  with 
this  gas. 

The  pleasant  pungency  of  brisk  and  sparkling  fermented  liquors 
is  owing  to  the  Carbonic  acid  which  they  hold  in  solution,  and 
which  they  lose  upon  exposure  to  the  air,  and  thereby  become  flat 
and  stale. 

It  possesses  acid  properties. — This  may  be  shown  by  dipping  into  wa- 
ter impregnated  with  it,  a  bit  of  litmus  paper,  or  by  mixing  with  a 
portion  of  the  liquid  about  an  equal  bulk  of  infusion  of  litmus  ;  in  both 
cases  the  litmus  will  be  reddened.  This  fact  establishes  the  title  of 
the  gas  to  be  ranked  among  acids.  When  an  infusion  of  litmus,  which 
has  been  thus  reddened,  is  either  heated  or  exposed  to  the  air,  its  blue 
colour  is  restored,  in  consequence  of  the  escape  of  carbonic  acid. 
This  is  a  marked  ground  of  distinction  from  most  other  acids,  the  effect 
of  which  is  permanent,  even  after  boiling. 

It  produces  turbidness  and  precipitation  when  passed  through  lime 
water. — This  is  produced  by  the  combination  of  the  lime  with  the  gas, 
forming  carbonate  of  lime,  which,  from  its  insolubility  in  water,  at 
first  renders  the  solution  milky,  and  afterwards  forms  a  white  flaky 
precipitate.  Hence  lime  water  is  not  only  a  valuable  test  of  the  pres- 
ence of  carbonic  acid,  but  is  frequently  used  to  withdraw  it  altogeth- 
er from  any  gaseous  mixture  that  contains  it ;  but  in  order  to  effect 
its  entire  absorption,  recourse  must  be  had  to  a  solution  of  caustic 
potassa  or  soda. 

SOURCES  AND  PREPARATION.  Carbonic  acid  is  produced  in  several 
cases  of  combustion  ;  and  also  during  the  process  of  respiration.  It 
is  moreover  a  constant  ingredient  of  atmospheric  air.  See  page  126. 

It  may  be  artificially  prepared  by  burning  carbon,  either  pure  char- 
coal or  the  diamond,  in  oxygen  gas.  But  it  is  most  conveniently  ob- 
tained, for  the  purposes  of  experiment,  by  the  action  of  muriatic  acid, 
diluted  with  two  or  three  times  its  weight  of  water,  on  fragments  of 
marble.  The  muriatic  acid  unites  with  the  lime,  forming  a  muriate  of 
lime,  and  carbonic  acid  gas  escapes,  with  effervescence.  It  may  also 
be  obtained  by  subjecting  any  of  the  carbonates,  and  especially  carbon- 
ate of  lime,  to  heat  in  an  iron  retort. 

ACTION  ON  THE  ANIMAL  ECONOMY.  When  an  attempt  is  made  to  in- 
spire pure  carbonic  acid,  a  violent  spasm  of  the  glottis  takes  place, 
which  prevents  the  gas  from  entering  the  lungs.  If  it  be  so  much  di- 
luted with  air  as  to  admit  of  its  passing  the  glottis,  it  then  acts  as  a 
narcotic  poison  on  the  system,  [t  is  this  gas  which  has  often  proved 
destructive  to  persons  sleeping  in  a  confined  room  with  a  pan  of  burn- 
ing charcoal. 

REFERENCES.  ChaptaPs  Chem.  iii.  12,  containing  a  detailed  account  of 
Carbonic  Acid.  Sanssure  on  the  quantity  of,  in  the  Atmosphere,  Ann.  de 
Ch.  et  de  Ph.  ii.  199,  and  Ann.  of  Phil.  ix.  41.  On  the  quantity  of  Car- 
bonic Acid  emitted  from  the  lungs  during  respiration,  at  different  titnes,  see 
the  very  able  papers  of  Prout,  in  the  Ann.  of  Phil.  ii.  328.  and  iv.  331. 
Faraday  on  the  liquefaction  of  Carbonic  Acid.  Ann.  of  Phil,  xxiii.  95. 
Brunei's  Apparatus  for  the  condensation  of}  into  a  liquid.  Repert.  of  Pat. 
Invent,  ii.  157. 


CARBON.  171 

SALTS    OF    CARBONIC    ACID    AND    AMMONIA. 

Carbonate  of  Ammonia— Atom.  Num.  39—Symb.  (3H+N) 

+(20+C.) 

r  A  dry  white  volatile  powder,  which  has  an  ammoniacal  odour  and 
alkaline  properties  ; — obtained  only  by  mixing  dry  carbonic  acid  over 
mercury  with  twice  its  volume  of  ammoniacal  gas. 

Sesquicarbonate  of  Ammonia. — Atom.    Num.  59 — Symb. 

(3H+N)+lJ(20+C)+lAq. 

SYN.     Subcarbonate  of  Ammonia — U.  S.  Phar. 

PROPERTIES.  When  fresh  prepared,  this  salt  has  a  crystalline  ap- 
pearance, and  some  transparency,  and  is  hard  and  compact ;  it  has  a 
pungent  smell,  and  a  sharp  penetrating  taste,  and  affects  vegetable 
blues  as  uncombined  alkalies  do  ;  it  dissolves  in  twice  its  weight  of 
cold,  or  an  equal  weight  of  boiling  water,  but  at  the  latter  temperature 
it  gives  off  part  of  its  acid  ;  when  exposed  to  the  atmosphere  it  loses 
weight  very  fast,  ceases  to  be  transparent,  and  becomes  inodorous, 
brittle,  and  easily  reducible  to  powder,  which  is  the  bicarbonate. 

PREPARATION.  The  sesquicarbonate  of  ammonia  is  prepared  by 
heating  a  mixture  of  one  part  of  muriate  of  ammonia  with  one  part 
and  a  half  of  carbonate  of  lime,  carefully  dried.  Double  decompo- 
sition ensues  during  the  process  ;  muriate  of  lime  remains  in  the  re- 
tort, and  the  sesquicarbonate  of  ammonia  is  sublimed.  The  carbonic 
acid  and  ammonia  are,  indeed,  in  proper  proportion  in  the  mixture  for 
forming  the  real  carbonate  ;  but  from  the  heat  employed  in  the  sub- 
limation, part  of  the  ammonia  is  disengaged  in  a  free  state. 

Bicarbonate  of  Ammonia — Atom.  Num.  61 — Symb.  (3H-J-N) 
+2  (20+C). 

Crystallizes  in  small  six  sided  prisms,  which  have  no  smell,  and  but 
little  taste.  It  was  formed  by  Berthollet  by  transmitting  a  current  of 
carbonic  acid  gas  through  a  solution  of  the  common  carbonate  of  am- 
monia of  the  shops.  On  evaporating  the  liquid,  the  bicarbonate  is  de- 
posited in  a  crystalline  form. 

REFERENCES.  Ure^s  Experimental  Researches  on  the  Ammoniacal  Salts, 
Ann.  of  Phil.  x.  203,  278.  R.  Phillips  on  the  Carbonate  of  Ammonia,  fyc. 
Brande^s  Jour.  vii.  294.  Same  author  QJI  the  Bicarbonate  of  Ammonia,  Ann. 
of  Phil.  xvii.  110. 

CARBON    AND    CHLORINE. 

For  our  knowledge  of  two  compounds  of  these  bodies,  we  are  indebt- 
ed to  the  able  researches  of  Mr.  Faraday.  [Phil.  Trans.  1821.]  An- 
other was  first  described  by  M.  Julin  of  Abo.  [Ann.  of  Phil.  xvii.  216.] 
And  recently  a  fourth  has  been  added  by  Liebig.  The  composition  of 
these  chlorides  will  be  seen  by  the  following  table  : 


172  CARBON. 

Subchloride  of  Carbon,    ....  C1+2C=  47-45 

Protochloride  of  Carbon,  -         -                  -  Cl-f  C=  41-45 

New  Chloride  of  Liebig,  -         -        -        -  2iCl-f-2C=100-63 

Perchloride  of  Carbon,      ....  3Cl-f-2C=118-35 

Subchloride  of  Carbon. — This  compound  was  discovered,  in  smal 
quantities,  by  M.  Julin,  in  a  manufactory  of  nitric  acid,  from  nitre  and 
sulphate  of  iron,  in  Sweden.  It  is  in  the  form  of  white  feathery  crys- 
tals, rather  heavier  than  water,  and  insoluble  in  that  fluid.  It  has  a  pe- 
culiar smell,  resembling  spermaceti,  and  is  tasteless.  It  is  soluble  in 
alcohol  and  ether,  and  burns  in  the  flame  of  a  lamp,  with  a  greenish 
colour.  It  was  made  the  subject  of  analysis  by  Messrs.  R.  Phillips  and 
Faraday. 

Protochloride  af  Carbon. — A  limpid  and  colourless  fluid  ;  does  not 
assume  the  solid  form  even  at  0°  F. ;  is  volatilized  at  160J  or  170°  F. ; 
may  be  distilled  without  change,  but  is  partly  decomposed  at  a  red 
heat;  sp.  gr.  1-5526. 

PREPARATION.  This  compound  is  obtained  by  passing  the  vapour 
of  perchloride  of  carbon  through  an  ignited  glass  tube  containing  frag- 
ments of  glass  or  rock  crystal,  to  increase  the  heated  surface.  The 
perchloride  is  partly  decomposed,  chlorine  escapes  and  a  fluid  passes 
over  which  may  be  separately  condensed  and  is  the  protochloride. 

Perchloride  of  Carbon. — A  transparent  colourless  brittle  solid,  hav- 
ing an  aromatic  odour  resembling  that  of  camphor  ;  sp.  gr.  2,  being 
exactly  double  that  of  water ;  fuses  at  320°  F.,  boils  at  360  J,  and  may 
be  distilled  without  change,  assuming  a  crystalline  form  as  it  condens- 
es ;  burns  vividly  in  oxygen  gas,  and  with  a  red  light  when  held  in 
the  flame  of  a  spirit  lamp  ;  is  soluble  in  alcohol,  ether,  and  in  the  fix- 
ed and  volatile  oils,  but  sparingly  so  in  water. 

This  chloride  is  obtained  by  mixing  olefiant  gas  (a  compound  of  chlo- 
rine and  hydrogen,)  with  chlorine,  arid  exposing  the  oily  liquid  which 
results  from  their  combination  to  the  direct  solar  rays,  in  a  vessel  full 
of  chlorine  gas.  The  chlorine  acts  upon  and  decomposes  the  liquid, 
muriatic  acid  is  liberated  and  the  carbon  at  the  moment  of  separation, 
unites  with  chlorine. 

REFERENCES.  Faraday's  Memoir,  containing  a  detailed  account  of  the 
two  last  compounds,  republished  from  the  Plnl.  Trans,  in  the  Ann.  of  Phil. 
xviii.  104. 

New  Chloride  of  Licbig. — A  limpid,  colourless  liquid,  similar  in  odour 
and  appearance  to  the  oily  fluid  which  chlorine  forms  with  olefiant 
gas  ;  density  1-48;  boils  at  141°  F. ;  is  soluble  in  alcohol  and  ether, 
but  not  in  water ;  is  feebly  combustible  and  is  not  changed  at  moderate 
temperatures  either  by  acids  or  alkalies. 

The  new  chloride  may  be  conveniently  prepared  by  distilling  from 
a  capacious  retort,  a  mixture  of  1  pound  of  chloride  of  lime,  3  pounds 
of  water,  and  2  or  3  ounces  either  of  alcohol  or  pyro-acetic  spirit. 


CARBON.  173 

CARBONIC    OXIDE    AND    CHLORINE. 

Chlorocarlonic  Add — Atom.  Num.  49*45 — Symb.  (O+C)+ 
Cl.  Sp.gr.  34421  air=l. 

This  compound  was  discovered  in  1812  by  Dr.  John  Davy,  who  des- 
cribed it  in  the  Philosophical  Transactions  for  that  year,  under  the 
name  of  Phosgene  Gas.  It  is  made  by  exposing  a  mixture  of  equal 
measures  of  dry  chlorine  and  carbonic  oxide  gases  to  sunshine,  when 
rapid  but  silent  combination  ensues,  and  they  contract  to  one-half 
their  volume.  Diffused  day-light  also  effects  their  union  slowly  ;  but 
they  do  not  combine  at  all  when  the  mixture  is  wholly  excluded  from 
light. 

PROPERTIES.  A  colourless  gas,  having  a  strong  odour,  and  redden- 
ing dry  litmus  paper.  It  combines  with  four  times  its  volume  of  am- 
moniacal  gas,  forming  a  white  solid  salt ;  so  that  it  possesses  the 
characteristic  property  of  acids.  By  contact  with  water  it  is  changed 
into  muriatic  and  carbonic  acid  gases.  Several  of  the  metals  decom- 
pose it,  and  unite  with  the  chlorine,  evolving  carbonic  oxide,  equiva- 
lent in  volume  to  the  original  gas. 

Chlorocarbonic  acid  then  affords  an  example  of  an  acid  with  a  sim- 
ple base,  and  two  acidifying  principles,  oxygen  and  chlorine,  which 
are  not  often  united  in  the  performance  of  this  function. 

Chloral. — This  name,  derived  from  the  first  syllable  of  the  words 
chlorine  and  alcohol,  has  been  applied  by  Liebig  to  a  new  compound  of 
chlorine,  carbon  and  oxygen  prepared  by  the  mutual  action  of  alcohol 
and  chlorine.  It  is  a  colourless,  transparent  liquid  of  a  penetrating 
pungent  odour,  and  nearly  tasteless,  or  at  most  oily  ;  it  boils  at  201° 
F.  and  may  be  distilled  without  change.  Liebig  considers  it  to  con- 
sist of  9  atoms  of  carbon,  6  chlorine,  and  4  oxygen.  For  details  con- 
cerning the  properties  and  mode  of  preparation  of  this  substance,  see 
Ann.  de  Chim.  et  de  Phys.  xlix.  146.  Also.  Turner's  Chem.  4th  Land. 
Ed. 

CARBON    AND    BROMINE. 

Bromide  of  Carbon. — This  compound  is  formed  by  mixing  together 
one  part  of  iodide  of  carbon  and  two  parts  of  bromine.  Bromides 
of  carbon  and  of  iodine  are  formed,  the  latter  of  which  is  removed  by  a 
solution  of  caustic  potash.  It  is  a  colourless  liquid,  at  common  tem- 
peratures, but  crystallizes  at  32°  F.  It  has  a  sweetish  taste,  an  ethe- 
real odour,  is  very  volatile  and  scarcely  soluble  in  water. — Berzelius,  i. 
360.  Ann.  de  Chim.  et  de  Phys.  xxxix.  225. 

CARBON    AND    IODINE. 

Periodide  of  Carbon. — When  a  solution  of  pure  potassa  in  alcohol  is 
mixed  with  an  alcoholic  solution  of  iodine,  a  portion  of  alcohol  is  de- 
composed ;  and  its  hydrogen  and  carbon,  uniting  separately  with 
iodine,  give  rise  to  periodide  of  carbon  and  hydriodic  acid.  The  latter 
combines  with  the  potash  and  remains  in  solution.  The  former  has  a 
yellow  colour,  like  sulphur,  and  forms  scaly  crystals  of  a  pearly  lustre  ; 
its  taste  is  very  sweet  and  it  has  a  strong  aromatic  odour  resembling 
saffron. — Ann.  de  Chim.  and  de  Phys.  xxxvii.  86. 

L 


174  CARBON. 


CARBON  AND  HYDROGEN. 

Chemists  have  for  several  years  been  acquainted  with  two  distinct 
compounds  of  carbon  and  hydrogen,  the  carburetted  hydrogen,  and 
the  olefiant  gas.  Besides  these,  a  third  has  been  pointed  out  by  Mr. 
Dalton,  as  entering  into  the  composition  of  oil  and  coal  gas.  to  which 
he  proposes  that,  provisionally,  the  name  of  Super- Olefiant  Gas  should 
be  given  ;  and  Mr.  Faraday  has  further  enlarged  our  knowledge  of 
these  compounds,  by  making  us  acquainted  with  at  least  two  others. 
[Phil.  Trans.  1825.]  According  to  Dr.  Thomson,  naphtha  and  naph- 
thaline, are  likewise  pure  hydrurets  of  carbon. 

The  following  is  a  table  of  the  gaseous  compounds  of  carbon  and 
hydrogen : 

1.  Hydruret  of  carbon,  (Olefiant  gas,)         12  C.+2  H.=14. 

2.  Bihydruret  of  carbon,       .        .         .          6  C.-J-2  H.=8. 

3.  Super-olefiant,          ....         18  C.-f  3  H.=21. 

4.  Bicarb.  Hyd.  ....        36  C.+3  H.=39. 

5.  Quadrocarb.  Hyd.  .        .        .        24C.+4H.=28. 

It  should  be  remarked,  however,  that  Thenard  does  not  consider  the 
compounds  described  by  Faraday,  as  distinct ;  and  Berzelius,  by  not 
noticing  them  in  his  treatise  in  connection  with  the  other  compounds, 
seems  to  incline  to  the  same  opinion.  At  all  events,  their  nature  is 
by  no  means  clearly  established,  and  I  shall  therefore  only  present  a 
brief  notice  of  them,  and  refer  to  authorities,  as  a  guide  to  those  who 
wish  to  examine  the  subject  more  at  length. 

Hydruret  of  Carbon— Atom.  Num.  H.—Symb.  2  H+2  C.  Sp. 
gr.  0-9709  air=l. 

SYN.     Olefiant  Gas.     Bicarburetted  or  Percarburretted  Hydrogen. 

This  gas  was  discovered  in  1796,  by  some  associated  Dutch  chem- 
ists, who  gave  it  the  name  of  Olefiant  Gas.  But  the  above  name  ap- 
pears to  be  more  in  conformity  with  the  principles  of  chemical  no- 
menclature. 

PROPERTIES.  A  colourless  elastic  fluid,  which  has  no  taste,  and 
scarcely  any  odour  when  pure  ;  is  absorbed  by  water  to  the  amount  of 
about  one-eighth  of  the  volume  of  the  latter  ;  it  extinguishes  flame,  is 
unable  to  support  the  respiration  of  animals,  and  when  set  on  fire,  as 
it  issues  from  the  orifice  of  a  small  pipe,  burns  slowly,  with  the  emis- 
sion of  a  dense  white  light ;  when  mingled  with  a  proper  quantity  of 
oxygen  gas,  it  forms  a  mixture  which  may  be  kindled  by  flame  or  the 
electric  spark,  and  which  explodes  with  great  violence  ;  it  is  decom- 
posed by  being  passed  through  red  hot  tubes  of  porcelain,  and  it  then 
deposits  its  carbon,  and  is  expanded  into  twice  its  original  volume  of 
hydrogen  ;  it  is  powerfully  acted  on  by  chlorine,  uniting  with  it,  as 
well  as  with  iodine,  at  ordinary  temperatures. 

When  olefiant  gas  is  mixed  with  oxygen  and  fired,  it  explodes. — If  the 
mixed  gases  are  fired  by  electricity  in  a  Volta's  eudiometer,  it  is  apt, 
unless  very  small  quantities  be  employed,  to  burst  the  instrument. — 
One  volume  requires  three  volumes  of  pure  oxygen  gas,  and  affords 
two  volumes  of  carbonic  acid  gas.  But  in  order  to  insure  the  perfect 
combustion  of  the  inflammable  gas,  it  should  be  mixed  with  five  times  its 


CARBON.  1 75 

bulk  of  oxygen  of  at  least  90  per  cent,  purity.  If  too  little  oxygen  be 
used,  charcoal  is  apt  to  be  precipitated  unburned  ;  and  a  small  excess  of 
oxygen  does  no  harm,  but  remains  in  the  mixture.  When  fired  with 
less  than  its  own  bulk  of  oxygen,  the  separation  of  charcoal  is  evident, 
and  the  bulk  of  the  residue  is  greater  than  that  of  the  original  gases. — 
Henry's  Cliem.  i.  444. 

It  may  be  decomposed  by  heat. — When  it  is  passed  through  a  porce^ 
lain  tube  at  a  low  red  heat,  charcoal  is  deposited,  and  an  equal  volume 
of  the  bihydruret  of  carbon  is  produced  ;  but  at  a  white  heat,  the  lat- 
ter is  also  decomposed,  and  the  gas  is  greatly  increased  in  volume. 

It  is  powerfully  acted  on  by  chlorine. — When  olefiant  gas  and  chlorine 
are  mixed  together  in  the  proportion  of  one  measure  of  the  former  and 
two  of  the  latter,  they  form  a  mixture  which  takes  fire  on  the  approach 
of  flame,  and  which  burns  rapidly  with  the  formation  of  murialic  acid 
gas,  and  deposition  of  a  large  quantity  of  charcoal.  But  if  the  gases 
are  allowed  to  remain  at  rest  after  being  mixed  together,  a  very  differ- 
ent action  ensues.  The  chlorine,  instead  of  decomposing  the  olefiant 
gas,  enters  into  direct  combination  with  it,  and  a  yellow  liquid-like  oil 
is  generated.  This  substance  is  sometimes  called  Chloric  Ether;  but 
the  term  Chloride  of  Hydrocarbon,  as  indicative  of  its  composition,  is 
more  appropriate.  Iodine  and  bromine  also  form  similar  compounds 
with  olefiant  gas,  all  of  which  we  shall  notice  hereafter. 

PREPARATION.  This  gas  may  be  obtained  by  mixing  in  a  large  glass 
retort,  three  measures  of  strong  sulphuric  acid,  and  one  measure  of 
alcohol,  or  spirits  of  wine,  and  applying  heat ;  the  mixture  soon  as- 
sumes a  black  colour  and  thick  consistence,  and  a  copious  disengage- 
ment of  gaseous  matter  takes  place,  which  may  be  collected  over  wa- 
ter or  mercury.  After  agitation  with  lime-water  or  solution  of  potas- 
sa,  to  separate  carbonic  and  sulphurous  acids,  pure  hydruret  of  carbon 
remains. 

In  order  to  understand  the  theory  of  this  process,  it  is  necessary  to 
state,  that  alcohol  is  supposed  to  consist  of  one  proportion  of  olefiant 
gas  and  one  of  water.  The  separation  of  the  water  is  effected  by  the 
sulphuric  acid,  for  which  it  is  known  to  possess  a  great  attraction. — 
The  first  portions  which  escape  from  the  mixture,  consist  of  ether, 
which  will  be  understood  from  the  fact,  that  ether  consists  of  two  pro- 
portions of  olefiant  gas,  combined  with  one  of  water,  differing  there- 
fore from  alcohol  in  the  amount  of  water  which  it  contains,  being  in 
this  respect  intermediate  between  alcohol  and  olefiant  gas. 

Pihydruret  of  Carbon— Atom.   Num.  S—Symb.  2  H-f  C— 
Sp.  gr.  0-5554  air=l. 

SYN.  Heavy  inflammable  air.— -Gas  of  marshes. — Hydrocarburet  and 
Protocarburet  of  Hydrogen. — Light  Carburetted  Hydrogen. 

The  real  nature  of  this  gas  was  first  ascertained  by  Dal  ton,  and  it 
has  since  been  examined  by  Sir  H.  Davy,  Thomson  and  Henry. 

PROPERTIES.  A  colourless,  permanent  gas,  soluble  in  very  minute 
proportions  in  water,  with  little  odour  ;  it  extinguishes  all  burning 
bodies,  and  is  of  course  unable  to  support  the  respiration  of  animals  ; 
it  is  highly  inflammable,  and  when  a  jet  of  it  is  set  on  fire,  it  burns  with 
a  yellowish  flame,  and  much  stronger  light  than  is  given  out  by  hydro- 
gen gas  ;  when  mixed  with  atmospheric  air  or  oxygen,  in  certain  pro- 


176  CARBON. 

portions,  it  explodes  with  violence  upon  contact  with  flame  ;  it  is  in 
part  only  resolved  into  its  elements  by  the  most  intense  heat. 

When  mixed  with  oxygen  gas  and  fired,  it  explodes.  To  decompose 
this  gas  completely,  it  is  necessary  to  mix  it  with  rather  more  than 
twice  its  bulk  of  oxygen  gas  ;  but  exactly  two  volumes  are  consumed. 
Water  and  a  quantity  of  carbonic  acid  are  produced,  the  latter  being 
precisely  equal  to  the  original  bulk  of  the  inflammable  gas. 

ACTION  OF  CHLORINE. — When  the  bihydruret  of  carbon  and  chlorine 
are  mixed  together  over  water,  no  action  takes  place  if  light  be  care- 
fully excluded ;  but  if  exposed  to  the  light  of  day,  and  still  more 
rapidly  in  the  light  of  the  sun,  a  series  of  decompositions  ensue.  Mu- 
riatic and  carbonic  acids  are  farmed,  the  former  of  which  is  instantly 
absorbed. 

PREPARATION  AND  NATIVE  STATE.  This  compound  of  carbon  and 
hydrogen  may  be  obtained,  mixed,  however,  with  about  1-20  of  car- 
bonic acid,  and  1-15  or  1-20  of  nitrogen  gas,  by  stirring  the  bottom  of 
almost  any  stagnant  pool  of  water,  especially  if  formed  of  clay. — 
When  this  is  done  by  an  assistant,  the  gas  is  copiously  disengaged  in 
bubbles,  which  may  be  collected  either  in  an  inverted  glass  jar,  or  in 
an  inverted  bottle  filled  with  water,  into  the  mouth  of  which  a  funnel 
is  fixed.  It  should  be  washed,  when  collected,  with  lime  water  or 
liquid  potassa.  It  may  also  be  procured  by  the  purification  of  gas 
from  coal,  by  means  of  chlorine  and  solution  of  potassa,  applied  in 
succession. 

Bicarburct  of  Hydrogen. — Atom.  Num.  39 — Symb. 
3H+60. 

When  oil  gas  is  subjected,  in  proper  vessels,  to  a  pressure  of  thirty 
atmospheres,  a  fluid  is  deposited  in  the  proportion  of  nearly  a  gallon 
from  1000  cubic  feet,  which  may  be  drawn  of  and  preserved  in  glass 
bottles  of  ordinary  strength.  By  repeated  distillations,  and  by  expo- 
sing the  distilled  liquid  to  a  temperature  of  zero,  Mr.  Faraday  obtain- 
ed a  substance  to  which  he  has  applied  the  above  name. 

The  bicarburet  of  hydrogen,  at  common  temperatures,  is  a  colour- 
less transparent  liquid,  which  smells  like  oil  gas,  and  has  also  a  slight 
odour  of  almonds  ;  its  specific  gravity  is  nearly  0.85  at  60°  F. ;  at 
32°  it  is  congealed,  and  forms  dendritic  crystals  on  the  sides  of  the 
glass  ;  at  zero  is  transparent,  brittle,  and  pulverulent,  and  is  nearly  as 
hard  as  loaf-sugar ;  when  exposed  to  the  air,  at  the  ordinary  tempera- 
ture it  evaporates,  and  boils  at  186°  ;  it  is  only  slightly  soluble  in  wa- 
ter, but  freely  so  in  alcohol  and  ether,  fixed  and  volatile  oils  ;  it  is  com- 
bustible and  forms  a  powerful  detonating  mixture  with  oxygen. 

Quadro carburet  of  Hydrogen. — Atom.  Num.  28 — Symb. 
4H+4C. 

The  second  carburet  of  hydrogen  discovered  by  Mr.  Faraday,  to 
which  the  above  name  has  been  applied,  was  derived  from  the  same 
source  as  the  preceding.  It  is  obtained  by  heating  with  the  hand  the 
condensed  liquid  from  oil  gas,  and  conducting  the  vapour  which 
escapes  through  tubes  cooled  artificially  to  zero.  A  liquid  is  thus 


CARBON.  177 

procured,  which  boils  by  slight  elevation  of  temperature,  and  before 
the  thermometer  rises  to  32-  F.,  is  wholly  reconverted  into  vapour. 

This  vapour  at  60°  F.  is  highly  combustible,  and  burns  with  a  bril- 
liant flame ;  has  the  specific  gravity  of  27  or  28,  hydrogen  being  1  ; 
it  is  sparingly  absorbed  by  water,  but  alcohol  takes  it  up  in  large  quan- 
tities, and  the  solution  effervesces  on  being  diluted  with  water  ;  olive 
oil  dissolves  about  six  times  its  volume,  and  one  volume  of  sulphuric 
acid  condenses  above  100  volumes  of  the  vapour  with  the  evolution  of 
great  heat ;  the  acid  is  much  blackened,  and  on  dilution  becomes  tur- 
bid, but  gives  out  no  gas. 

The  vapour  on  being  cooled  down  to  0°  F.  is  again  condensed  into 
a  liquid,  which  when  examined  in  a  tube  hermetically  sealed,  has  a 
specific  gravity  of  0  627  at  54°  ;  it  is  therefore  the  lightest  fluid  known., 
—Henry,  1 ,  450. 

REFERENCES.  Faraday  in  Phil.  Trans,  for  1825,  or  Ann.  of  Phil. 
xxvii.  44. 

Naphtha  from  Coal  Tar.     And  Naphthaline. 

Both  these  substances  are  obtained  by  distillation  from  coal  tar. — 
The  former  has  received  its  name  from  its  similarity  to  mineral  naph- 
tha. It  has  a  strong  and  peculiar  empyreumatic  odour,  and  is  highly 
inflammable.  Potassium  may  be  preserved  in  it  without  loosing 
Its  lustre.  It  is  composed  according  to  Dr.  Thomson,  of  six  atoms 
carbon  and  six  atoms  hydrogen=42. 

Naphthaline,  is  a  white  crystalline  solid,  heavier  than  water  ;  has  a 
pungent  aromatic  taste,  and  a  peculiar  faintly  aromatic  odour;  it 
freezes  at  180°  F.  and  assumes  a  crystalline  texture  in  cooling  ;  it 
volatilizes  slowly  at  common  temperatures  and  boils  at  410°  F.  ;  is  not 
very  readily  inflamed,  but  when  set  on  fire  burns  rapidly,  and  emits  a 
large  quantity  of  smoke  ;  insoluble  in  cold  and  sparingly  soluble  in  hot 
water,  but  freely  so  in  alcohol  and  ether ;  is  not  acted  upon  by  the 
alkalies,  but  is  dissolved  by  the  acetic  and  oxalic  acids  forming  pink 
coloured  solutions  and  combines  with  sulphuric  acid  ;  it  probably  con- 
sists of  1  atom  hydrogen  and  3  atoms  carbon=19. 

Naphthaline  combines  with  sulphuric  acid. — By  the  combination  of  these 
two  substances  an  acid  is  formed  which  was  first  described  by  Mr. 
Faraday  in  1826.  under  the  name  of  Sulpho-Naphthalic  Acid.  It  has  a 
bitter  acid  taste,  reddens  litmus  powerfully  and  combines  with  bases 
forming  salts  which  are  called  Sulpho-Napthalates. — Faraday  in  PhiL 
Trans,  for  1826. 

MIXED  COMBUSTIBLE  GASES  FROM  MOIST  CHARCOAL,  ALCOHOL, 
ETHER,  COAL,  OIL,  TALLOW  AND  WAX — FIRE  DAMP. 

The  preceding  compounds  of  carbon  and  hydrogen,  are  the  only 
ones  which  are  considered  as  distinct  and  definite  compounds,  and 
perhaps,  two  of  these  are  not  yet  entitled  to  be  so  considered.  It  is  of  a 
mixture  of  two  or  more  of  these,  with  occasionally  a  portion  of  carbon- 
ic oxide,  that  the  almost  infinite  variety  of  aeriform  products  are 
constituted,  which  are  obtainable  by  the  exposure  of  moistened  char- 
coal, of  alcohol  or  ether,  of  oil,  tallow,  wax,  resin  or  coal,  to  a  heat  a 
little  above  ignition. 


178  CARBON. 

Of  these  aeriform  compounds,  the  gases  from  coal  and  from  oil,  are 
of  most  importance,  from  their  widely  extended  use  in  artificial  illumi- 
nation. 

Coal  Gas. — By  submitting  coal  to  distillation  in  an  iron  retort,  be- 
sides a  portion  of  tar  and  a  solution  of  carbonate  of  ammonia,  which 
condense  in  a  liquid  form,  a  large  quantity  of  permanent  gas  is  evolv- 
ed. This  gas  is  very  variable  in  its  composition  and  properties,  not 
only  when  prepared  from  different  coals,  but  from  the  same  kind  of 
coal  under  different  circumstances. — [Henry,  Phil.  Trans.  J808  and 
1820.]  The  general  term  of  coal  gas  is,  therefore,  quite  indefinite, 
and  it  is  probably  a  mixture  of  several  varieties  of  carburetted  hydro- 
gen with  hydrogen  gas,  carbonic  oxide,  carbonic  acid,  nitrogen,  and 
sulphuretted  hydrogen  gases. — Henry's  Chem.  i.  452. 

Coal  gas,  as  generally  procured,  has  a  very  disagreeable  odour, 
arising  from  sulphuretted  hydrogen,  and  perhaps  a  little  sulphuret  of 
carbon  ;  but  these  may  be  removed  by  passing  it  through  lime  sus- 
pended in  water,  by  agitation.  The  specific  gravity  of  the  purified 
gas  varies  from  0*450  to  0-700.  A  large  quantity  of  an  impure  carbon, 
called  coke,  is  found  in  the  retorts,  after  the  extraction  of  the  gas. 

It  is  scarcely  possible  to  assign  the  quantity  of  gas,  which  ought  to 
be  obtained  from  a  given  weight  of  coal,  but  it  may  be  considered  as 
an  approach  to  a  general  average  to  state,  that  112  Ibs.  of  good  coal 
are  capable  of  giving  from  450  to  500  cubic  feet  of  gas,  of  such  quali- 
ty that  half  a  cubic  foot  per  hour  is  equivalent  to  a  mould  candle  of 
six  to  the  pound,  burning  during  the  same  space  of  time. — Henry's 
Che,,i.  i.  453. 

Oil  Gas. — Oil,  by  being  allowed  to  trickle  into  a  red  hot  retort,  half 
filled  with  coke  or  pieces  of  brick  to  increase  the  heated  surface,  is  de- 
composed, and  yields  a  large  quantity  of  gas,  which  is  much  richer  in 
carburetted  hydrogen  than  coal  gas,  and  is,  therefore,  much  better  fit- 
ted for  purposes  of  illumination.  Its  specific  gravity  varies  from 
0'800  to  0-950.  It  contains  no  admixture  of  sulphuretted  hydrogen, 
and  requires  no  purification.  It  is,  however,  more  expensive  than  the 
coal  gas.  See  an  Essay  ly  Drs.  Turner  and  Christison  in  the  Edin.  PhiL 
Jour.  xiii.  1. 

It  has  also  been  ascertained,  by  Mr.  Daniell,  that  rosin  by  peculiar 
treatment,  yields  an  abundance  of  gas,  equal  in  quality  to  that  from 
oil,  and  at  about  one-fourth  of  the  expense ;  its  smell  moreover  is 
much  less  offensive  than  that  of  either  coal  or  oil  gas,  and  it  has  been 
introduced  with  success  in  several  large  establishments  in  England. — 
L.  U.  K. 

Fire  Damp. — The  fire  damp  of  coal  mines  was  proved  by  an  analysis 
of  Dr.  Henry,  [Nicholson's  Jour.  xix.  149,]  to  be  identical  in  compo- 
sition, with  light  carburetted  hydrogen.  This  gas  often  issues  in  large 
quantity  from  between  beds  of  coal,  and  by  collecting  in  mines,  owing 
to  deficient  ventilation,  gradually  mingles  with  atmospheric  air,  and 
forms  an  explosive  mixture.  The  first  unprotected  light  which  then 
approaches,  sets  fire  to  the  whole  mass,  and  a  dreadful  explosion  en- 
sues. These  accidents  are  now,  however,  comparatively  rare,  owing 
to  the  employment  of  the  Safety-Lamp.  For  this  invention  we  are 
indebted  to  Sir  H.  Davy  ;  and  its  utility  depends  upon  the  principles 
which  have  already  been  adverted  to  in  the  remarks  upon  the  causes 
which  modify  combustion. 


CARBON.  179 

REFERENCES.  For  the  methods  of  separating  the  various  impurities  from 
Coal  Gas,  see  the  papers  of  Dr.  Henry,  in  the  Phil.  Trans,  for  1808  and  1820, 
or  Ann.  of  Phil.  xiv. — An  abstract  of  the  analytical  part  of  these  papers  is 
given  in  the  %d  volume  of  his  Elements  of  Chemistry.  The  Essay  of  Dry. 
Turner  and  Chrislison,  above  quoted,  contains  much  practical  information 
concerning  Oil  and  Coal  Gas.  The  article  Gas  Lights,  in  the  Supplement  to 
the  Encyclopedia  Britannica,  by  Mr.  Creighton.  DanieWs  patent  for  pre. 
paring  Gas  from  Rosin,  in  Brandt's  Jour.  N.  8.  \.  217.  The  Treatises  on 
Gas  Lights,  by  Mr.  Accum  and  Mr.  Peckston  and  by  Dr.  Cooper.  Davy  on 
the  Safety-Lamp  for  coal  miners,  Lond.  1818,  containing  a  full  history  of  the 
Lamp,  and  of  the  chemical  researches  connected  with  it. 

OLEPIANT    GAS    AND    CHLORINE. 

Chloride  of  Hydrocarbon. — Atom.  Num.  49*35 — Symb. 
(2H+2C)+Ci. 

SYK.  Hydrocarburet  of  Chlorine.     Chloric  Ether. 

Discovered  by  the  Dutch  chemists  ;  but  its  true  nature  was  first  as- 
certained by  Dr.  Thomson,  [Mem.  Wernerian  Soc.  1,]  and  more  fully 
elucidated  by  M.  M.  Robiquet  and  Colin. — Ann.  de  Chim.  et  de  Phys. 
i.  and  ii. 

PROPERTIES.  When  pure  it  is  a  colourless  volatile  liquid,  of  a  pe- 
culiar sweetish  taste  and  ethereal  odour ;  has  a  specific  gravity  of 
1-2201  at  45°  F.;  boils  at  152°  F.  and  may  be  distilled  without 
change;  is  decomposed  by  passing  its  vapour  through  a  red  hot 
porcelain  tube,  being  resolved  into  charcoal,  bihydruret  of  carbon, 
(light  carbureted  hydrogen, )  and  muriatic  acid  gas. 

PREPARATION,  This  compound  may  be  obtained,  as  before  stated, 
by  allowing  a  mixture  of  chlorine  and  olefiant  gases  to  remain  at  rest. 
The  oily  liquid  which  is  generated  is  to  be  washed  with  water  and  then 
distilled  from  chloride  of  calcium,  when  the  compound  is  obtained  in 
its  pure  and  dry  form. 

OLEFIANT    GAS    AND    BROMINE. 

Bromide  of  Hydrocarbon. — Atom.  Num.  92*26 — Symb.  ^ 

(2H+2C)+Br. 

Discovered  by  M.  Serullas.— Ann.  de  Chim.  et  de  Phys.  xxxiv.  95. 

PROPERTIES.  A  colourless  liquid,  heavier  than  water,  very  volatile, 
of  a  penetrating,  ethereal  odour,  and  of  a  very  sweet  taste,  which  it 
communicates  to  water  in  which  it  is  placed,  in  consequence  of  being 
slightly  soluble  in  that  liquid  ;  it  is  solid  at  a  temperature  between  21° 
and  23°  F.  and  then  resembles  camphor. 

PREPARATION.  According  to  Serullas,  this  compound  is  best  ob- 
tained by  bringing  two  parts  of  bromine  into  contact  with  one  of 
iodide  of  hydrocarbon  ;  the  products  being  bromide  of  iodine  and  bro- 
mide of  hydrocarbon. 


180  CARBON. 


OLEFIANT    GAS    AND    IODINE. 

Iodide  of  Hydrocarbon — Atom.   Numb.   140 — Symb. 

(2H+2C)+I. 

Discovered  by  Mr.  Faraday.— Phil.  Trans.  1821.  Ann.  of  Phil 
xviii.  104. 

PROPERTIES.  A  solid  white,  crystalline  body,  which  has  a  sweet 
taste  and  an  aromatic  odour  ;  it  sinks  rapidly  in  boiling  sulphuric 
acid  ;  it  is  fused  by  heat  and  then  sublimed  without  change,  condens- 
ing into  crystals,  which  are  either  tabular  or  prismatic  ;  on  exposure 
to  heat  it  is  decomposed  and  iodine  escapes  ;  it  burns,  if  held  in  the 
flame  of  a  spirit  lamp,  with  evolution  of  iodine  and  some  hydriodic 
acid ;  it  is  insoluble  in  water  and  in  acid  or  alkaline  solutions,  but 
dissolves  in  alcohol  or  ether,  and  crystallizes  upon  evaporating  the 
solution. 

PREPARATION.  This  compound  may  be  obtained  by  exposing  ole- 
fiant  gas  and  iodine  contained  in  the  same  vessel,  to  the  direct  rays  of 
the  sun. 

CARBON    AND    NITROGEN. 

Nitruret  of  Carbon,  or  Cyanogen. — Atom.  Num.  26 — Symb. 
N+2C— 8p.  gr.  1-804  air=l. 

Discovered  by  Gay  Lussac,  in  1815. — [Ann.  de  Chim.  xcv.  and  Ann. 
of  Phil.  viii.  37.]  Its  properties  have  also  since  been  investigated  by 
Vauquelin. — Ann.  of  Phil.  xiii.  430. 

PROPERTIES  A  colourless  gas  with  a  strong,  pungent  and  very 
peculiar  odour;  at  the  temperature  of  45°  F.  and  under  a  pressure 
of  3*6  atmospheres,  it  is  a  limpid  liquid,  which  resumes  the  gaseous 
form  when  the  pressure  is  removed  ;  it  extinguishes  burning  bodies, 
but  it  is  inflammable  and  burns  with  a  beautiful  and  characteristic 
purple  flame  ;  it  is  not  decomposed  by  the  strongest  heat ;  water,  at 
the  temperature  of  60°  F.  absorbs  4-5  times,  and  alcohol  23  times  its 
volume  of  the  gas  ;  its  specific  gravity,  according  to  Gay  Lussac,  is 
1-8042;  though  a  compound  body,  cyanogen  has  a  great  tendency  to 
combine  with  elementary  substances. 

Cyanogen  is  absorbed  by  water. — The  aqueous  solution  reddens  lit- 
mus ;  this,  however,  is  scarcely  to  be  considered  as  an  effect  of  the 
gas  itself,  but  is  owing  to  the  presence  of  acids  which  are  generated 
by  the  mutual  decomposition  of  cyanogen  and  water.  [  Vauquelin.  Ann. 
of  Phil.  xiii.  430.]  By  long  keeping,  a  strong  solution  was  found  by 
Vauquelin  to  assume  a  light  amber  colour,  and  to  deposit  orange  yel- 
low crystals,  which  he  proposes  to  call  subcyanogen. — Ann.  of  Phil. 
N.  S.  vi.  68. 

It  unites  with  elementary  substances. — This  property,  which  is  some- 
what peculiar  in  the  case  of  a  compound  body,  is  illustrated  by  heat- 
ing potassium  in  cyanogen  gas ;  an  energetic  action  ensues,  the  metal 
becomes  incandescent,  and  a  cyanide  of  potassium  is  generated.  On 
the  other  hand  the  affinity  of  cyanogen  for  the  metallic  oxides  is  com- 
paratively feeble.  Hence  it  can  have  no  claim  to  the  character  of  an 
acid. 


CARBON.  181 

PREPARATION.  Cyanogen  does  not  exist  in  nature,  but  may  be  pre- 
pared by  the  decomposition  of  the  cyanide  of  mercury,  a  compound 
which  will  be  described  hereafter. 

This  substance,  well  dried,  at  a  temperature  below  that  of  boiling 
water,  is  put  into  a  small  glass  retort,  or  a  common  test  tube,  to  the 
open  end  of  which  a  cork  is  accurately  fitted.  Through  this  is  passed 
a  smaller  pipe,  which  may  be  straight  or  bent  at  right  angles.  The 
cyanide  of  mercury  is  put  into  the  tube,  the  open  end  of  which  is  clos- 
ed by  the  cork.  Heat  is  now  applied  ;  the  cyanide  first  blackens,  then 
liquifies,  and  the  cyanogen  comes  over  in  the  form  of  gaet,  which  may 
be  collected  over  mercury  ;  or  its  combustibility  and  the  peculiar  colour 
of  its  flame  may  be  exhibited  by  bringing  a  taper  into  contact  with  the 
gas  as  it  issues  from  the  orifice  of  the  pipe. 


Cyanous  Acid. — (Cyanic  Acid  of  W older.) 

First  obtained  in  a  state  of  combination  by  Wohler,  and  for  some 
time  known  only  in  that  form.  Subsequently  the  same  chemist  dis- 
covered a  method  of  obtaining  the  pure  cyanous  acid.  This  consists 
in  subjecting  to  heat  the  anhydrous  cyanic  acid.  A  part  of  the  acid 
sublimes  without  change,  while  another  part  is  transformed  into  cya- 
nous acid  with  the  disengagement  of  nitrogen  and  of  carbonic  acid  ; 
when  the  receiver  is  properly  cooled,  the  anhydrous  cyanous  acid  con- 
denses upon  the  inner  side,  in  the  form  of  a  transparent  colourless 
liquid. 

This  acid  has  a  penetrating  odour,  is  very  volatile,  and  irritates  the 
eyes  strongly.  When  combined  with  water,  heat  is  produced,  and  it 
is  converted  into  carbonate  of  ammonia. — Bcrzdius,  ii.  155. 

Cyanous  acid  may  be  readily  obtained  in  combination  with  potassa, 
by  calcining,  at  a  red  heat,  equal  weights  of  anhydrous  ferrocyanate  of 

*  The  nature  of  the  properties  of  the  compounds  of  cyanogen  arid  oxygen  is 
said  to  have  been  well  cleared  up  in  a  recent  memoir  by  M.  M.  Wohler  and 
Liebig.  [Ann.  de  Chim.  xlvi.  25.]  But  as  there  is  still  some  uncertainty  on 
the  subject,  and  as  it  would  require  much  detail  to  explain  these  views,  I 
content  myself,  at  present,  with  the  following  notice  of  their  investigations 
from  Johnston's  Report.  They  have  shown  that  the  cyanic  acid  of  Serullas 
contains  hydrogen  according  to  the  formula  1  1-2  (Cy-f-20+H),  and  have 
given  it  the  name  of  Cyanuric  Acid.  This  acid  distills  over  without  loss, 
and  condenses  in  the  cooled  receiver  into  a  limpid  colourless  liquid,  which  is 
the  cyanic  acid  of  Wohler  combined  with  one  atom  of  water.  It  is  repre- 
sented by  the  formula  (Cy-}-0)-f-(H+0),  in  which  the  elements  are  precise- 
ly in  the  same  ratio  as  in  the  cyanuric  acid,— from  which  it  appears  that  by 
heat  the  atoms  constituting  cyanuric  acid  are  arranged  so  as  to  produce  one 
atom  and  a  half  of  a  hydrated  cyanic  acid  containing  one  atom  water.  But  this 
new  arrangement  of  the  atoms  is  very  unstable  ;  for  on  acquiring  the  tempr. 
rature  of  the  atmosphere  it  begins  to  grow  turbid,  evolves  heat,  enters  into 
ebullition,  and  in  a  few  minutes  is  converted  into  a  dry,  compact,  brilliant? 
white  solid,  of  the  same  composition  as  the  cyanuric  and  hydrated  Cyanic 
acids,  and  which,  from  its  insolubility  in  water  and  nitric  and  muriatic  acids* 
has  been  called  insoluble  cyanuric  acid. 


182  CARBON. 

potassa  and  peroxide  of  manganese.  Pulverize  the  remaining  mass  and 
boil  with  alcohol  86  per  cent,  pure  ;  on  cooling,  thecyanite  of  potassa 
separates, [in  small  plates,  resembling  the  chlorate  of  potassa.  [  W'dhler, 
Ann.  de  Chim.  et  de  Phys.  xxvii.  196.]  From  its  combination  with  po- 
tassa the  acid  may  be  transferred  by  double  decomposition  to  other 
bases  ;  but  we  are  not  yet  acquainted  with  any  method  of  separating 
the  pure  cyanous  acid  from  the  cyanites. 

It  should  be  remarked  that  this  acid  is  identical  in  its  composition 
with  that  which  was  discovered  by  Liebig,  in  1 823,  to  exist  in  the  ful- 
minating compounds  of  mercury  and  silver,  and  which  he  then  de- 
nominated Fulminic  Acid,  as  he  called  the  compounds  Fulminates.  Ac- 
cording to  an  analysis  of  fulminating  silver,  made  by  M.  M.  Liebig 
and  Gay  Lussac,  the  acid  of  the  salt  is  composed  of  26  parts  or  one 
proportion  of  cyanogen  and  8  parts  or  one  of  oxygen.  [Ann.  de  Chim. 
et  de  Phys.  xxiv.]  It  is,  therefore,  if  this  view  be  correct,  a  real  Cy- 
anous Acid,  and  the  compounds  should  be  termed  Cyanites.  Berzelius, 
however,  thinks  it  difficult  to  admit,  without  more  proof,  the  identity 
of  the  composition  of  these  two  acids. — Trait,  de  Chim.  ii.  159. 

Cyanic  Acid. 

This  acid  is  obtained,  according  to  Serullas,  by  the  action  of  hot 
water  upon  the  perchloride  of  cyanogen,  to  be  presently  noticed  ;  mu- 
riatic acid  and  a  new  acid  compound  of  cyanogen  and  oxygen  are  the 
results.  Evaporation  expels  the  muriatic  acid  and  leaves  a  true  cyanic 
acid,  capable  of  existing  in  a  separate  form,  and  possessing,  indeed, 
considerable  stability  of  composition,  since  it  affords  crystals  which 
may  be  repeatedly  dissolved,  re-crystallized,  and  which  even  dissolve 
without  change,  in  nitric  and  sulphuric  acids.  With  bases  it  forms  a 
distinct  class  of  salts,  properly  called  Cyanates.  Carefully  analyzed, 
this  acid  was  found  to  consist  of  one  proportion  of  cyanogen  and  two 
proportions  of  oxygen. — Serullas,  Ann.  de  Chim.  et  de  Phys.  for  Aug. 
1828.  For  Wohler's  process,  see  Berzelius,  ii.  160. 

CYANOGEN  AND    CHLORINE. 

There  appears  to  be  two  distinct  compounds  of  chlorine  and  cyano- 
gen, which  have  been  termed  Chloride  and  Perchloride  of  Cyanogen. 

Chloride  of  Cyanogen. — Atom.   Num.  6145 — Syrnb.  C1-J- 
(N+2C.) 

SYN.  Cyanide  of  Chlorine.  Chlorocyanic  Acid.  Chloride  Cyaneux. 
— Berzelius. 

Discovered  by  Berthollet,  and  subsequently  examined  by  Gay  Lug- 
gac  [Ann.  de  Chim.  xcv.  ]  and  by  Serullas — [Ann.  de  Chim.  et  de  Phys. 
Aug.  1827,]  by  whom  it  was  first  obtained  in  a  state  of  purity. 

PROPERTIES.  Chloride  of  cyanogen  is  remarkable  in  the  circum- 
stance of  its  crystallizing  in  long  slender  needles,  at  the  temperature 
of  0°  F.  (by  this  it  is  separated  from  portions  of  other  gases,  with 
which  it  would  otherwise  be  liable  to  be  contaminated ;)  it  becomes 
liquid  at  about  8°  or  10°  F.  and  at  68°  F.  is  a  gas  equivalent  to  four  at 
mospheres  ;  in  the  liquid  state  it  is  as  limpid  and  colourless  as  water ; 


CARBON.  183 

it  has  a  very  offensive  odour,  irritates  the  eyes,  is  corrosive  to  the  skin, 
and  highly  injurious  to  animal  life  ;  reddens  vegetable  blue  colours, 
and  does  not  explode  when  mixed  either  with  oxygen  or  hydrogen 
gases. 

PREPARATION.  If  cyanide  of  mercury  be  mixed  with  just  sufficient 
water  to  reduce  it  to  a  semi-fluid  state,  and  exposed  to  the  action  of 
gaseous  chlorine,  in  the  course  of  a  few  hours  the  colour  of  the  chlo- 
rine will  disappear,  and  a  gas  will  be  found  in  its  place,  which  is  not 
absorbable  by  mercury,  but  instantly  taken  up  by  water.  This  is  the 
chloride  of  cyanogen  or  chlorocyanic  acid.  One  portion  of  the  chlo- 
rine, in  this  process,  expels  the  cyanogen  from  the  mercury,  and 
forms  bichloride  of  mercury,  while  another  portion  combines  with  the 
cyanogen  and  forms*  the  new  compound. — For  details,  see  Henry's 
Cfiem.  and  Turner.  See  also,  Gay  Lussac  in  Ann.  of  Phil.  viii.  47. 

Perchloride  of  Cyanogen. —A torn.  Num.  96-90—  Symb.  2C1+ 
(N+2C.) 

SYM.     Chloride  Cyanique — Berzelius. 

Discovered  by  Serullas. — Ann.  de  Chim.  Aug.  1828. 

PROPERTIES  When  carefully  purified  and  dried  it  is  brilliantly 
white  and  crystallizes  in  needles  ;  its  specific  gravity  is  1  '320  ;  it 
fuses  at  140°,  and  boils  at  190°  ;  when  kept  for  some  time,  it  exhales 
on  opening  the  bottle,  an  odour  of  muriatic  acid  ;  it  is  sparingly  soluble 
in  cold  water,  but  dissolves  in  hot,  though  with  partial  decomposi- 
tion ;  it  is  extremely  poisonous,  a  single  grain  having  proved  fatal  to  a 
rabbit. 

PREPARATION.  The  process  of  Serullas  is  to  pour  about  155  grains 
of  pure  hydrocyanic  acid  of  Gay  Lussac  into  a  bottle  containing  about 
61  cubic  inches  of  dry  chlorine.  The  bottle  being  closed  with  a  stop- 
per, and  exposed  to  sun-light,  the  hydrocyanic  acid  is  vaporized  ;  and 
after  a  few  hours  a  colourless  liquid  is  seen  on  the  inner  surface  of  the 
bottle,  having  the  appearance  of  water,  which  becomes  thicker  and 
thicker,  and  finally  in  about  twenty-four  hours,  sets  into  a  white 
solid,  mixed  with  shining  crystals.  The  process  is  one  of  some 
delicacy,  and  requires  the  observance  of  several  precautions,  which  are 
given  at  length  in  the  original  memoir,  above  referred  to. — Henry,  i. 

CYANOGEN    AND    BROMINE. 

Bromide  of  Cyanogen. — Atom.  Num.  104-26 — Symb.  Br.-f- 
(N+2C.) 

This  compound  has  been  obtained  by  M.  Serullas,  by  a  process  anal- 
ogous to  that  for  preparing  chloride  of  cyanogen.  The  properties  al- 
so closely  resemble  those  of  that  compound,  as  well  as  of  iodide  of  cy- 
anogen.— Ann.  de  Chim.  et  de  Phys.  xxxiv.  and  xxxv. 


184  CARBON, 

\ 

CYANOGEN    AND    IODINE. 

Iodide  of  Cyanogen. — Atom.  Num.  152—Symb.  I+(N+2C.) 

Obtained  by  Serullas  by  heating,  in  a  wide  mouthed  phial,  a  mix- 
ture ,of  one  part  iodine  and  two  parts  cyanide  of  mercury,  both  per- 
fectly dr  y.  When  the  cyanide  of  mercury  begins  to  be  decomposed, 
and  the  violet  vapour  of  iodine  ceases  to  be  produced,  the  phial  is 
placed  inclined  under  an  inverted  bell-shaped  glass,  the  mouth  of 
which  is  then  closed  with  a  piece  of  paper  or  disk  of  glass.  White 
vapours  arise  from  the  phial,  and  are  condensed  in  fine  cotton-like 
flocks  on  the  surface  of  the  paper  or  glass  disk.  To  purify  these  from 
some  adhering  cyanide  of  mercury,  they  are  resublimed  at  the  gentlest 
heat  adequate  to  that  effect. 

The  properties  of  this  compound  are  analogous  to  those  of  chloride 
of  cyanogen.—  Ann.  de  Chim.  et  de  Pkys.  xxvii. 

CYANOGEN    AND   HYDROGEN. 

Hydrocyanic  or  Prussic  Acid. — Atom.  Num.  27. — Symb. 
H+(N+2C.) 

Discovered  by  Scheele  in  1782,  but,  as  it  was  aflerwards  found,  in 
solution  in  water.  First  procured  in  a  pure  state  by  Gay  Lussac. 

PROPERTIES.  Pure  hydrocyanic  acid  is  a  limpid  and  colourless 
fluid,  of  a  strong  odour,  similar  to  that  of  peach  blossoms  ;  its  taste  is 
first  cool,  but  soon  becomes  hot  and  acrid  ;  its  specific  gravity  at  45° 
F.,  is  0-7058 ;  it  is  highly  volatile  ;  boils  at  79°  F.,  and  at  zero  con- 
geals ;  a  drop  of  it  placed  on  a  piece  of  glass  becomes  solid,  because 
the  cold  produced  by  the  evaporation  of  one  portion  is  so  great  as  to 
freeze  the  remainder  ;  it  unites  with  alcohol  and  water  in  all  propor- 
tions ;  is  liable  to  spontaneous  decomposition,  and  cannot  be  preserv- 
ed for  any  length  of  time,  even  when  out  of  contact  of  air,  in  well  stop- 
ped bottles  ;  is  highly  poisonous ;  reddens  litmus  paper  feebly,  and 
combines  with  bases  forming  salts,  which  are  called  Hydrocyanatcs  or 
Prussiates. 

PREPARATION.  The  best  process  for  preparing  hydrocyanic  acid, 
is  that  proposed  by  Vauquelin.  It  consists  in  rilling  a  narrow  tube 
placed  horizontally,  with  fragments  of  cyanide  of  mercury,  and  caus- 
ing a  current  of  sulphuretted  hydrogen  gas  to  pass  slowly  along  it. — 
The  instant  that  gas  comes  in  contact  with  the  cyanide,  double  de- 
composition ensues,  the  sulphur  of  the  gas  combines  with  the  metal, 
forming  black  sulphuret  of  mercury,  and  the  cyanogen,  which  is  lib- 
erated, unites  with  the  hydrogen.  The  acid  may  be  expelled  by  a  very 
gentle  heat,  and  collected  in  a  receiver  kept  cool  by  ice. 

This  acid  may  also  be  obtained  by  moistening  the  cyanide  of  mer- 
cury with  muriatic  acid,  and  distilling  at  a  low  temperature.  This  is 
the  process  adopted  at  Apothecaries'  Hall  in  London. — See  Webster's 
Brande. 

TESTS.  The  presence  of  free  hydrocyanic  acid  is  easily  recognized 
by  its  odour.  When  in  combination,  it  may  be  detected  by  adding  to 
the  liquid  supposed  to  contain  it,  a  solution  of  green  vitriol,  throwing 
down  the  protoxide  of  iron  by  a  slight  excess  of  pure  potassa,  and  af- 


CARBON.  185 

ter  exposure  to  the  air  for  four  or  five  minutes,  acidulating  with  mu- 
riatic or  sulphuric  acid,  so  as  to  redissolve  the  precipitate.  Prussian 
blue  will  then  make  its  appearance,  if  hydrocyanic  acid  had  been  ori- 
ginally present. 

As  hydrocyanic  acid  is  sometimes  administered  with  criminal  de- 
signs, the  chemist  may  be  called  on  to  search  for  its  presence  in  the 
stomach  after  death.  This  subject  has  been  investigated  experimental- 
ly by  M.  M.  Leuret  and  Lassaigne,  and  the  process  they  have  recom- 
mended is  the  following.  The  stomach  or  other  substances  to  be  ex- 
amined are  cut  into  small  fragments,  and  introduced  into  a  retort  along 
with  water,  the  mixture  being  slightly  acidulated  with  sulphuric  acid. 

The  distillation  is  then  conducted  at  a  temperature  of  212°  F.,  the 
volatile  products  collected  in  a  receiver  surrounded  with  ice,  and  the 
presence  of  hydrocyanic  acid  in  the  distilled  matter,  tested  by  the  me- 
thod above  mentioned.  These  gentlemen  found  that  prussic  acid  may 
be  thus  detected  two  or  three  days  after  death  ;  but  not  after  a  long- 
er period.  The  disappearance  of  the  acid  appears  owing  partly  to  its 
volatility,  and  partly  to  the  facility  with  which  it  undergoes  sponta- 
neous decomposition. — Journal  de  C/dmie  Medicate,  ti?c.  xii.  561. — Tur- 
ner. See  also,  Christison  on  Poisons,  555. 

ACTION  ON  THE  ANIMAL  ECONOMY.  Pure  hydrocyanic  acid  is  a  pow- 
erful poison,  producing  insensibility  and  convulsions,  which  are 
speedily  followed  by  death.  A  single  drop  of  it  placed  on  the  tongue 
of  a  dog  causes  death  in  the  course  of  a  very  few  seconds  ;  and  small 
animals,  when  confined  in  its  vapour.,  are  rapidly  destroyed.  On  in- 
spiring the  vapour,  diluted  with  atmospheric  air,  headach  and  giddi- 
ness supervene  ;.  and  for  this  reason  the  pure  acid  should  not  be  made 
in  close  apartments  during  warm  weather.  The  distilled  water  from 
the  leaves  of  the  Prunus  lauro  ccrasus  owes  its  poisonous  quality  to  the 
presence  of  this  acid.  Its  effects  are  best  counteracted  by  diffusi- 
ble stimulants,  and  of  such  remedies,  solution  of  ammonia  appears  to 
be  the  most  beneficial. 

This  acid  in  its  diluted  form  is  sometimes  employed  in  medical  prac- 
tice to  diminish  pain  and  nervous  sensibility.  It  may  be  procured  of 
any  strength  by  dissolving  cyanide  of  mercury  in  water,  and  transmit- 
ting a  current  of  sulphuretted  hydrogen  gas  through  the  solution  till 
the  whole  of  the  cyanide  is  decomposed  ;  which  may  be  known  by 
the  filtered  liquid  remaining  colourless  and  transparent  when  mixed 
with  a  solution  of  sulphuretted  hydrogen. 

REFERENCES.  Gay  LussaJs  experiments  on  Prussic  Acid,  Ann.  de  Chim. 
xcv.  136,  or  Ann.  of  Phil,  vii.  350,  viii.  37, 108.  PorretCs  Memoir  on  Prus- 
sic  Acid,  Trans,  Lond.  Soc.  of  Arts,  fyc,  xxvii.  89.  For  details  concerning 
its  action  on  the  human  system,  and  its  medical  employment,  see  Magendie's 
Formulary — also  Beckys  Med.  Juris.  540,  and  Randolph  on  the  deleterious 
effects  of  Hydrocyanic  Acid^  Amer.  Med.  Rec.  iv.  456. 

HYDROCYANIC    ACID    AND    AMMONIA. 

Hydrocyanate  of  Ammonia. 

This  salt  crystallizes  in  cubes  or  in  very  small  prisms.  Its  volatility 
is  such,  that  at  a  temperature  of  72°  F.  its  vapour  supports  a  column 
of  upwards  of  15  inches  of  mercury  ;  and  at  97°  F.,  it  is  equal  to  the 


186  CARBON. 

pressure  of  the  atmosphere.  Dr.  Thomson  finds,  that  when  prussian 
blue  is  exposed  to  a  red  heat  in  a  copper  tube,  and  the  products  re- 
ceived over  mercury,  the  glass  receiver  is  coated  with  transparent  crys- 
tals of  this  salt.  The  solution  of  this  salt  precipitates  several  metal- 
lic solutions  not  affected  by  hydrocyanic  acid,  which,  according  to 
Scheele,  acts  only  on  nitrates  of  silver  and  mercury,  and  on  carbonate 
of  iron. — Ann.  of  PkiL  xv.  394.  Henry's  Chem.  i.  480. 

CYANOGEN    AND    SULPHUR. 

Cyanide  of  Sulphur. 

This  compound  was  first  formed  by  Lassaigne.  Into  a  small  glass 
balloon  he  puts  a  little  cyanide  of  mercury  finely  pulverized,  and  pours 
upon  it  half  its  weight  of  bichloride  of  sulphur.  At  the  end  of  14  or 
15  days  of  exposure  to  day-light,  the  balloon  being  closed  so  as  to  ex- 
clude air,  a  minute  quantity  of  crystals  rise  to  the  upper  part  of  the 
balloon,  which  are  the  acid  in  question. 

Like  the  sulphocyanic  acid,  with  which  it  may  possibly  be  identical, 
it  forms  crimson  coloured  salts,  with  the  peroxide  of  iron. — Ann.  de 
Ch.  et  de  Ph.  Oct.  1828.  Henry,  i.  500. 

Sulphocyanic  Acid. — Atom.   Num.   59 — Symb.  H+ 

(N+2C+2S) 

SYN.     Anthrazothionic  Acid. — Grotthuss. 

This  acid  was  discovered  in  the  year  1808,  by  Mr.  Porrett,  who  as- 
certained that  it  is  a  compound  of  sulphur,  carbon,  hydrogen,  and  ni  - 
trogen,  and  described  it  under  the  name  of  Sulphuretted  Chyazic  Acid. 
It  is  now  more  commoly  called  Sulphocyanic  Acid,  and  its  salts  are 
termed  Sulphocyanates. 

PROPERTIES.  A  transparent  liquid,  which  is  either  colourless  or  has 
a  slight  shade  of  pink  ;  odour  somewhat  similar  to  that  of  vinegar  ; 
the  strongest  solution  of  it  which  Mr.  Porrett  could  obtain,  had  a 
specific  gravity  of  1-022  ;  it  boils  at  216-5°F.  and  at  54.5°  crystallizes 
in  six-sided  prisms,  reddens  litmus  apper,  and  forms  neutral  compounds 
with  alkalies  ;  its  presence,  whether  free  or  combined,  is  easily  detect- 
ed by  a  persalt  of  iron,  with  the  oxide  of  which  it  unites,  forming  a 
soluble  salt  of  a  deep  blood-red  colour  ;  with  the  protoxide  of  copper 
it  yields  a  white  salt,  which  is  insoluble  in  water. 

PREPARATION.  This  acid  is  obtained  by  mixing  so  much  sulphuric 
acid  with  a  concentrated  solution  of  the  sulphocyanate  of  potassa  as 
is  sufficient  to  neutralize  the  alkali,  and  then  distilling  the  mixture. — 
An  acid  liquor  collects  in  the  recipient,  which  is  sulphocyanic  acid 
dissolved  in  water,  and  sulphate  of  potassa  remains  in  the  retort. 

REFERENCES.  The  memoirs  of  T.  von  Grotthuss ,  Vogel,  and  R.  Porrett, 
Jun.  in  Ann.  of  Phil.  xiii.  39,  89,  101,  356. 


CARBON.  187 

CARBON   AND  SULPHUR. 

Bisulphuret  of  Carbon,  or  Alcohol  of  Sulphur. 

Discovered  in  1796  by  Professor  Lampadius,  who  regarded  it  as  a 
compound  of  sulphur  and  hydrogen,  and  termed  it  Alcofiol  of  Sulphur. 
Its  true  nature  was  first  pointed  out  by  Clement  and  Desormes. 

PROPERTIES.  A  transparent  colourless  liquid,  remarkable  for  its 
high  refractive  power ;  specific  gravity  1 '272  ;  has  an  acid,  pungent, 
and  somewhat  aromatic  taste,  and  a  nauseous  and  very  fetid  smell  ;  is 
very  volatile,  and  boils  at  the  common  atmospheric  pressure  at  a  tem- 
perature not  exceeding  110°  F  ;  owing  to  its  volatility,  it  may  be  em- 
ployed for  producing  an  intense  degree  of  cold  ;  it  has  never  been  con- 
gealed by  the  lowest  artificial  temperature  ;  is  highly  inflammable,  and 
burns  with  a  blue  flame,  emitting  copious  fumes  of  sulphurous  acid ; 
dissolves  readily  in  alcohol  and  ether,  and  is  precipitated  from  the 
solution  by  water  ;  dissolves  sulphur,  phosphorus  and  iodine ;  decom- 
poses chlorine,  with  the  formation  of  chloride  of  sulphur ;  combines 
with  the  alkalies  slowly,  forming  compounds  which  Berzelius  calls  Car- 
bosulphurets. 

PREPARATION.  This  compound  rnay  be  obtained  by  heating  in 
close  vessels  the  native  bisulphuret  of  iron,  (iron  pyrites,)  with  one- 
fifth  of  its  weight  of  well  dried  charcoal ;  or  by  transmitting  the  va- 
pour of  sulphur  over  fragments  of  charcoal  heated  to  redness  in  a  tube 
of  porcelain.  The  compound,  as  it  is  formed,  should  be  conducted 
by  means  of  a  glass  tube  into  cold  water,  at  the  bottom  of  which  it  is 
collected.  To  free  it  from  moisture  and  adhering  sulphur,  it  should 
be  distilled  at  a  low  temperature  in  contact  with  the  chloride  of  cal- 
cium. 

Xanthogen  and  Hydroxanthic  Acid. 

Professor  Zeise,  of  Copenhagen,  has  discovered  some  novel  and  in- 
teresting facts  relative  to  the  bisulphuret  of  carbon.  When  this  fluid 
is  agitated  with  a  solution  of  pure  potassa  in  strong  alcohol,  the  alka- 
line properties  of  the  potassa  disappear  entirely  ;  and  on  exposing  the 
solution  to  a  temperature  of  32°  F.,  numerous  acicular  crystals  are 
deposited.  Zeise  attributes  these  phenomena  to  the  formation  of  a 
new  acid,  the  elements  of  which  are  derived,  in  his  opinion,  partly 
from  the  alcohol,  and  partly  from  the  bisulphuret  of  carbon.  He  re- 
gards the  acid  as  a  compound  of  carbon,  sulphur  and  hydrogen.  He 
supposes  it  to  be  a  hydracid,  and  that  its  radical  is  a  sulphuret  of  car- 
bon. To  the  radical  of  this  hydracid,  he  applies  the  term  Xanthogen, 
(from  the  Greek  Xanthos,  yellow,  and  gennao  to  generate,)  expressive 
of  the  fact,  that  its  combinations  with  several  metals  have  a  yellow  co- 
lour. The  acid  itself  is  called  Hydroxanthic  Acid,  and  its  salts  Hydrox- 
anthates.  The  crystals  deposited  from  the  alcoholic  solution,  are  the 
hydroxanthate  of  potassa. 

It  appears  to  be  agreed  that  a  new  acid  is  generated  under  the  cir- 
cumstances described  by  M.  Zeise,  but  he  has  not  obtained  it  in  a  se- 
parate state,  and  there  is  considerable  uncertainty  concerning  its  na- 
ture. For  details  concerningit,  see  Ann.  de  Chim,  et  de  Phys.  xxi.,  and 
Ann.  of  Phil.  xx.  241. 


188  BORON. 

CARBON    AND    PHOSPHORUS. 

Phospliuret  of  Carbon. — Atom.  Num.  2l.7—Symb.~P+C. 

Discovered  by  Proust  in  1799,  but  first  obtained  in  a  pure  state  by 
Dr.  Thomson.— -Ann.  of  Phil.  viii.  157. 

PROPERTIES.  A  soft  powder  of  a  yellowish  colour,  without  taste  or 
smell ;  when  exposed  to  the  air,  it  slowly  imbibes  moisture,  and  ac- 
quires an  acid  flavour :  burns  when  exposed  to  a  red  heat,  gradually 
giving  out  phosphorus,  the  charcoal  being  prevented  from  burning  by 
a  coating  of  phosphoric  acid. 

This  compound  is  prepared  by  allowing  phosphuret  of  calcium  to 
remain  in  water  till  it  no  longer  evolves  gas ;  then  add  to  the  liquid 
excess  of  muriatic  acid,  agitate  for  a  few  moments,  and  throw  the 
whole  on  a  filter.  The  powder  which  remains  is  to  be  washed  and 
dried,  and  is  pure  phosphuret  of  carbon. 

SECTION  YI. 

BORON. 

Atom.  Num.  S—Symb.  B. 

First  obtained  by  Sir  H.  Davy  in  1808,  by  the  action  of  Voltaic  elec- 
tricity on  bqracic  acid.  Subsequently  in  greater  quantity  by  Gay 
Lussac  and  Thenard,  by  heating  boracic  acid  with  potassium. 

PROPERTIES.  Boron  is  a  dark  olive-coloured  substance,  which  has 
neither  taste  nor  smell,  and  is  a  non-conductor  of  electricity ;  insolu- 
ble in  water,  alcohol,  ether  and  oils ;  does  not  decompose  water 
whether  hot  or  cold  ;  bears  an  intense  heat  in  close  vessels,  without 
fusing,  or  undergoing  any  other  change,  except  a  slight  increase  of 
density  ;  its  specific  gravity  is  about  twice  as  great  as  that  of  water  ; 
it  may  be  exposed  to  the  atmosphere  at  common  temperatures  without 
change,  but  if  heated  to  600°  F.,  it  suddenly  takes  fire,  oxygen  gas 
disappears,  and  boracic  acid  is  generated ;  it  experiences  a  similar 
change  when  heated  in  nitric  acid,  or  with  any  substance  that  yields 
oxygen  with  facility. 

PREPARATION.  In  addition  to  the  above  methods  of  preparing  boron, 
that  of  Berzelius  should  be  noticed  as  the  easiest  and  most  economical 
method  of  producing  it.  This  consists  in  heating  the  potassium  in 
contact  with  the  fluoborate  of  potassa. — Berzelius ,  Traite.  de  Chim.  i. 
361.  Ann.  of  Phil.  xxvi.  128. 

BORON   AND    OXYGEN. 

Boracic  Add.— Atom.  Num.  24— Symb.  20+B — Sp.gr, 
1479.  water=l. 

SYN.  '  Homberg's  sedative  Salt. 

PROPERTIES.  Boracic  acid  has  the  form  of  thin  white  scales,  is 
destitute  of  smell  and  nearly  so  of  taste  ;  it  is  sparingly  soluble  in  wa- 
ter, and  the  solution  reddens  vegetable  blue  colours  ;  and,  what  is  verjs 
remarkable,  it  renders  turmeric  paper  brown  like  the  alkalies.  [Fara* 


BORON.  189 

day.']  It  is  soluble  in  alcohol,  and  communicates  a  beautiful  green  co- 
lour to  its  flame  ;  fuses  when  heated,  aad  gives  off  its  water  of  crystalli- 
zation to  the  amount  of  43  or  44  parts  in  the  hundred,  and  is  converted 
into  a  hard  colourless  transparent  glass,  which  is  anhydrous  boracic  acid 
the  hydrous  or  crystalline  acid  being  supposed  to  consist  of  one  pro- 
portion of  dry  acid  and  two  of  water. 

PREPARATION  AND  NATIVE  STATE.  As  a  natural  product,  this  acid  is 
found  in  the  hot  springs  of  Lipari,  and  in  those  of  Sasso  in  the  Flo- 
rentine territory.  It  is  a  constituent  of  several  minerals,  among  which 
the  datholite  and  boracite  may  in  particular  be  mentioned.  It  occurs 
much  more  abundantly  under  the  form  of  borax,  a  native  compound 
of  boracic  acid  and  soda.  It  is  prepared  for  chemical  purposes  by  ad- 
ding sulphuric  acid  to  a  solution  of  purified  borax  in  about  four  times 
its  weight  of  boiling  water,  till  the  liquid  acquires  a  distinct  acid  reac- 
tion. The  sulphuric  acid  unites  with  the  soda  ;  and  the  boracic  acid 
is  deposited,  when  the  solution  cools,  in  'a  confused  group  of  shining 
scaly  crystals.  It  is  then  thrown  on  a  filter,  washed  with  cold  water 
to  separate  the  adhering  sulphate  of  soda  and  sulphuric  acid,  and  still 
further  purified  by  solution  in  boiling  water  and  re-crystallization.  — 
But  even  after  this  treatment  it  is  apt  to  retain  a  little  sulphuric  acid, 
and  on  this  account,  when  required  to  be  absolutely  pure,  should  be 
fused  in  a  platinum  crucible,  and  once  more  dissolved  in  hot  water  and 
crystallized. 

REFERENCES.  Gay  Lussac  and  Thenard  on  the  decomposition  and  re- 
composition  of  Boracic  Acid,  Jour,  de  Phys.  1808,  'and  Repert.  of  Arts,  %d 
ser.  xiv.  408.  Robiquet  on  the  preparation  of  Boracic  Add  from  Tincal  and 
the  waters  of  Lakes  in  Tuscany  ,  Ann.  de  Chiin.  et  de  Phys.  ii.  203,  and  Re- 
pert,  of  Arts,  2o?  ser.  xxxvi.  123.  Faraday  on  the  action  of  Boracic  Acid  on 
Turmeric^  Branded  Jour.  vi.  152. 


BORON    AND    CHLORINE. 

Bichloride  of  Boron.—  Atom.  Num.  78-9—  Symb.  2C1+B— 
Sp.  gr.  3-942.  air=l. 

S  YN.     Chloride  Boriyue.  —  Berzelius. 

Boron  burns  with  considerable  splendour  in  chlorine  gas.  The  pro- 
duct Berzelius  finds  to  be  a  new  gas,  which  may  be  freed  from  excess 
of  chlorine  by  standing  over  mercury.  [Berzelius  Traitede  Chitn.  i.  365-6. 
Ann.  of  Phil.  xxvi.  129.  J  It  smokes  in  the  atmosphere  like  fluoboric 
acid  gas  ;  is  rapidly  absorbed  by  water  ;  is  soluble  also  in  alcohol  ; 
unites  with  ammoniacal  gas  forming  a  fluid  volatile  substance. 

The  combination  of  these  two  elements  has  been  better  effected  by 
Despretz,  by  passing  chlorine  over  boruret  of  iron,  and  also  by  trans- 
mitting the  same  gas,  deprived  of  water,  over  charcoal  and  boracic 
acid,  ignited  together  in  a  porcelain  tube.  —  PhiL  Mag.  and  Ann.  i. 
4o9. 


190  BORON- 

BORON    AND    CHLORINE. 

Fluoboric  Acid,  or  Fluoride  of  Boron. 

SYN.     Fluoride  Borique. — Berzelius. 

Discovered  in  1810  by  Gay  Lussac  and  Thenard.  Its  true  compo- 
sition does  not  yet  appear  to  be  understood. 

PROPERTIES.  Fluoboric  acid  gas  is  colourless,  has  a  penetrating 
pungent  odour,  and  extinguishes  flame  on  the  instant  ;  its  specific 
gravity,  according  to  Dr.  Thomson,  is  2'3622  ;  it  reddens  litmus  pa- 
per as  powerfully  as  sulphuric  acid,  and  forms  salts  with  alkalies  which 
are  called  Fluoborates ;  it  has  a  singular  great  affinity  for  water. — 
When  it  is  mixed  with  air  or  any  gas  which  contains  watery  vapour, 
a  dense  white  cloud  appears,  which  is  a  combination-  of  water  and 
fluoboric  acid  gas.  From  this  circumstance,  it  affords  an  exceedingly 
delicate  test  of  the  presence  of  moisture  in  gases*  Fluoborie  acid  gas 
is  rapidly  absorbed  by  water.  According  to  Dr.  John  Davy,  water 
absorbs  700  times  its  volume.  Caloric  is  evolved  during  the  absorp- 
tion and  the  water  acquires  an  increase  of  volume.  The  saturated 
solution  is  limpid,  fuming,  and  very  caustic.  On  the  application  of 
heat,  part  of  the  gas  is  disengaged  ;  but  afterwards  the  whole  solution 
is  distilled. 

This  acid  does  not  act  on  glass,  but  attacks  animal  and  vegetable 
substances  with  great  energy  ;  converting  them,  like  sulphuric  acid, 
into  a  carbonaceous  substance.  According  to  Berzelius,  when  in  a 
certain  state  of  dilution,  part  of  the  fluoboric  acid  and  water  mutually 
decompose  each  other,  with  formation  of  boracic  and  hydrofluoric 
acids.  The  latter  he  supposes  to  unite  with  undecomposed  fluoboric 
acid,  forming  what  he  has  called  Hydrqfluoboric  Acid.  [Traite  de  Ch~ 
ii.  189.]  A  different  view,  however,  is  maintained  by  Gay  Lussac  and 
Thenard. 

PREPARATION.  This  gas  may  be  obtained  by  subjecting  to  strong 
heat,  in  an  iron  tube,  a  mixture  of  one  part  of  dry  boracic  acid,  and 
two  parts  of  powdered  fluor  spar.  It  may  also  be  procured  by  mixing 
one  part  of  vitrified  boracic  acid,  and  two  of  fluor  spar,  with  twelve 
parts  of  strong  sulphuric  acid,  and  heating  the  mixture  gently  in  a 
glass  retort.  [Dr.  John  Davy,  Phil.  Trans,  for  1812.]  When  thus 
prepared,  however,  it  contains  fluosilicic  acid,  according  to  Berzelius, 
in  considerable  quantity  ;  and  Dr.  Thomson  detected  in  it  traces  of 
sulphuric  acid.  The  gas  may  likewise  be  formed  by  the  action  of  hy- 
drofluoric acid  on  a  solution  of  boracic  acid. 

REFERENCES.  Thenard,  Traite  de  Chim.  ii.  533.  Berzelius^  in  Ann.  of 
Phil.  xxvi.  122. 

BORON    AND    SULPHUR. 

Sulpliuret  of  Boron. 

SYN.     Suljide  Borique. — Berzelius. 

This  compound  may  be  formed,  according  to  Berzelius,  by  igniting 
boron  strongly  in  the  vapour  of  sulphur,  and  the  combination  is  ac- 
companied with  the  phenomena  of  combustion.  The  product  is  a 


SELENIUM.  191 

white  opaque  mass,  which  is  converted  by  the  action  of  water  into 
sulphuretted  hydrogen  and  boracic  acid  ;  and  the  liquid  becomes  milky 
at  the  same  time  from  the  deposition  of  sulphur. — Ann.  of  Phil.  xxvi. 
129.  Berzelius,  i.  365. 

SECTION  VII. 

SELENIUM. 
Atom.  Num.  40 — Symb.  Se— -$p.  gr.  4-3  water=l. 

Discovered  by  Berzelius,  in  1818. 

PROPERTIES.  Selenium  at  common  temperatures,  is  a  brittle  solid, 
of  a  brown  colour  and  metallic  fracture  ;  it  has  neither  taste  nor 
smell ;  when  pounded,  the  particles  stick  together,  and  its  powder 
has  a  deep  red  colour ;  it  melts  at  a  few  degrees  above  the  boiling 
point  of  water,  and  when  warm  is  very  ductile,  and  may  be  drawn 
into  fine  threads,  which  are  red  by  transmitted,  but  grey  by  reflected 
light  ;  it  boils  at  a  temperature  of  about  60(P  F.  and  condenses  either 
in  opaque  metallic  drops,  or,  when  large  vessels  are  used,  in  flowers  of 
the  colour  of  cinnabar ;  its  vapour  has  a  deep  yellow  colour  ;  when 
heated  in  the  flame  of  a  candle,  urged  by  a  current  of  air  from  a 
blow-pipe,  it  emits  a  strong  smell  of  horse-radish. 

When  selenium  was  first  discovered  it  was  regarded,  by  Berzelius, 
as  a  metal ;  but,  since  it  is  an  imperfect  conductor  of  caloric  and 
electricity,  it  more  properly  belongs  to  the  class  of  simple  non-metal- 
lic bodies.  It  is  still  very  rare,  and  many  accomplished  chemists  have 
never  yet  had  an  opportunity  of  seeing  it.  I  shall,  therefore,  be  quite 
brief  in  the  account  of  it  and  of  its  compounds. 

NATIVE  STATE  AND  EXTRACTION.  In  the  process  for  obtaining  sul- 
phuric acid  at  Fahlun,  in  Sweden,  from  a  natural  combination  of  sul- 
phur and  iron,  called  pyrites,  it  was  observed  that  a  reddish  mass  was 
deposited,  which  in  burning  gave  out  a  peculiar  odour.  The  princi- 
pal portion  of  the  mass  was  sulphur  ;  but  it  was  mixed  with  a  very 
minute  quantity  of  a  substance,  to  which  Berzelius  afterwards  gave 
the  name  of  selenium.  The  process  by  which  it  was  extracted  is  gi- 
ven at  length,  in  Ann.  of  P kit.  xiii.  403.  The  improved  method  of  M. 
Lewenau  is  also  given  in  the  24th  volume  of  that  work.  It  has  since 
been  discovered  in  the  volcanic  rocks  of  Lipari  ;  in  several  varieties 
of  sulphur  ;  and  in  sulphuric  acid  made  with  pyrites  obtained  from 
the  isle  of  Anglesea.  [Ann.  of  Phil.  xxiv.  and  xxv.]  Selenium  has 
also  been  discovered  by  M.  Henry  Rose,  in  several  minerals  from  the 
Eastern  Hartz,  united  with  lead,  cobalt,  copper  and  mercury — [Ann. 
de  Ch.  ct  de  Phys.  xxix.  113,]  and  Stromeyer  and  Haussman  have  ana- 
lyzed a  seleniui  ct  of  lead  from  the  Laurence  mine  at  Clausthal. — Ann. 
of  Phil.  xxvi.  233. 

REFERENCES.  On  this  substance  and  its  compounds,  see  a  detailed  notice 
in  Berzelius^  Trait  de  Chitn.  ii.  397 


SELENIUM    AND    OXYGEN. 

There  appear  to  be  three  distinct  compounds  of  selenium  and  oxygen, 
though  the  first  of  these  is  not  yet  well  understood. 


192  SELENIUM. 

Oxide  of  Selenium.— Atom.  Num.  48  ?—Sy?nb.  O+Se  ? 

Oxide  of  Selenium  is  formed  by  heating  selenium  in  a  close  phial 
with  common  air,  which  acquires  a  very  strong  smell  of  horse-rad- 
ish. Water  agitated  with  this  air  imbibes  the  odour  of  the  gas,  and 
reddens  litmus  feebly,  but  this  appears  to  be  owing  to  the  production 
of  a  small  quantity  of  selenious  acid. 

Oxide  of  selenium  is  a  colourless  gas,  which  is  very  sparingly  solu- 
ble in  water,  and  does  not  possess  any  acid  properties.  Its  compo- 
sition has  not  yet  been  determined,  but  it  probably  contains  an  atom  of 
each  of  its  elements.  Berzelius,  to  whom  we  are  indebted  for  most 
that  is  known  concerning  it,  does  not  seem  to  have  yet  obtained  it  in 
a  perfectly  pure  state. — Ann.  de  Chim.  et  de  Phys.  ix.  176. 

Selenious  Acid. — Atom.  Num.  56—  Symb.  2O+Se. 

Discovered  by  Berzelius. 

PROPERTIES.  A  white  crystalline  substance,  having  a  sour  and 
slightly  burning  taste  ;  it  is  very  soluble,  both  in  water  and  in  alcohol; 
it  is  readily  decomposed  by  all  substances  which  have  a  strong  attrac- 
tion for  oxygen.  If  sulphurous  acid  be  passed  into  its  solution,  pure 
selenium  will  be  thrown  drown  in  the  state  of  a  red  powder,  and  sul- 
phuric acid  formed  ;  it  may  likewise  be  precipitated  by  the  immer- 
sion of  plates  of  zinc  or  polished  iron  ;  it  combines  with  bases  and 
forms  Selenites. 

PREPARATION.  This  acid  is  most  conveniently  prepared  by  digest- 
ing selenium  in  nitric  or  nitro-muriatic  acid,  till  it  is  completely  dis- 
solved. On  evaporating  the  solution  to  dryness,  a  white  residue  is 
left  which  is  selenious  acid.  By  increase  of  temperature,  the  acid 
itself  sublimes,  and  condenses  again  unchanged,  in  long  four-sided 
needles.  It  attracts  moisture  from  the  air,  whereby  it  suffers  imper- 
fect liquefaction. 

REFERENCE.     Berzelius,  ii.  405, 

Selenic  Acid.— Atom.  Num.  64 — Symb.  3O+Se. 

Discovered  by  Professor  Mitscherlich,  and  described  in  Ann.  de  Chim. 
et  de  Phys.  Sept.  1827.  and  in  Edin.  Jour,  of  Science,  viii.  294. 

PROPERTIES.  A  colourless  liquid,  which  may  be  heated  to  536°  F. 
without  sensible  decomposition,  but  at  554°  F.  is  resolved  into  oxy- 
gen and  selenious  acid  ;  its  specific  gravity,  when  freed  as  completely  as 
possible  from  water,  is  2'625  ;  but  even  when  of  this  density,  it  still 
contains  15-75  of  water  in  100  of  acid  ;  like  sulphuric  acid  it  evolves 
great  heat  when  suddenly  diluted.  When  heated  with  muriatic  acid, 
it  affords  chlorine  and  selenious  acid,  and  like  aqua  regia ,  dissolves 
gold. 

Selenic  acid  dissolves  iron  and  zinc  with  a  disengagement  of  hy- 
drogen ;  copper  with  an  evolution  of  selenious  acid,  and  gold,  but 
not  platinum.  In  its  affinities  for  bases  it  is  a  little  inferior  to  sul- 
phuric acid,  but  its  compounds,  (seleniate  of  baryta  for  example,)  are 
not  entirely  decomposed  by  the  latter  acid. 

PREPARATION.  This  acid  may  be  prepared  by  fusing  nitrate  of  po- 
tassa  with  selenium,  with  selenious  acid  or  with  a  seleniuret,  such  as 


SELENIUM.  193 

that  of  lead,  freed  from  earthy  impurities  by  muriatic  acid.  The  resi- 
due, amounting  to  about  one-third  of  the  whole,  is  mixed  with  an 
equal  weight  of  nitrate  of  soda  and  projected,  by  little  at  once,  into  a 
red-hot  crucible.  The  lead  is  oxidized,  and  the  selenium  is  convert- 
ed into  selenic  acid,  which  combines  with  the  soda.  The  purification 
of  the  seleniate  of  soda  involves  many  details,  which  may  be  found 
in  the  original  memoir  above  quoted. — [See  also  Turner's  Chemistry.'] 
The  last  step  of  the  process  consists  in  decomposing  seleniate  of  lead 
in  solution,  by  sulphuretted  hydrogen,  which  precipitates  sulphuret 
of  lead,  leaving  the  selenic  acid  in  such  a  state  as  to  be  purified  by 
ebullition. 


SELENIUM    AND    CHLORINE. 

Chloride  of  Selenium. 

Selenium  absorbs  chlorine  gas,  and  becomes  hot  and  forms  a  brown 
liquid,  which,  by  an  additional  quantity  of  chlorine  is  converted  into 
a  white  solid  mass.  This  is  stated  by  Berzelius  to  be  a  compound  of 
muriatic  and  selenic  acids,  but  it  is  probably  composed  of  chloride  of 
selenium  and  selenious  acid.  It  has  not  yet  been  accurately  separat- 
ed into  its  component  parts,  for  when  heat  is  applied,  both  substances 
are  sublimed. — Henry,  i.  424. 

SELENIUM    AND    BROMINE. 

Bromide  of  Selenium. 

This  compound  is  obtained,  according  to  Serullas,  by  causing  sele- 
nium to  fall,  in  small  portions,  upon  bromine.  They  combine  with 
violence,  and  with  the  disengagement  of  heat.  When  cold,  the  mass 
is  solid,  of  an  orange  colour,  and  soluble  in  water. — Berzelius,  ii.  419. 

SELENIUM    AND    HYDROGEN. 

Hydroselenic  Acid.-— Atom.  Num.  41 — Symb.  H+Se. 

SYN.     Seleniuretted  Hydrogen  Gas.     Selenide  Ht/drique. — Berzelius. 
Discovered  by  Berzelius  and  found  to  be  analogous  to  sulphuretted 
hydrogen. 

PROPERTIES.  A  colourless  acid,  with  an  odour  at  first  similar  to 
that  of  sulphuretted  hydrogen,  but  it  afterwards  irritates  the  lining 
membrane  of  the  nose*  powerfully,  excites  catarrhal  symptoms,  and 
destroys,  for  some  hours,  the  sense  of  smelling ;  it  is  absorbed  freely 
by  water,  forming  a  colourless  solution  which  reddens  litmus  paper, 
and  gives  a  brown  stain  to  the  skin.  The  acid  is  soon  decomposed  by 
exposure  to  the  atmosphere  ;  for  the  oxygen  of  the  air  unites  with  the 
hydrogen  of  the  hydroselenic  acid,  and  selenium,  in  the  form  of  a  red 
powder,  subsides. 

All  the  salts  of  the  common  metals  are  decomposed  by  hydroselenic 
acid.  The  hydrogen  of  that  acid  combines  with  the  oxygen  of  the 
oxide,  and  a  seleniuret  of  the  metal  is  generated. 


194  SELENIUM. 

PREPARATION.  This  gas  is  disengaged  by  the  action  of  muriatic 
acid  upon  a  concentrated  solution  of  an  hydroseleniate.  It  may  also 
be  procured  by  heating  the  seleniuret  of  iron  in  muriatic  acid.  By  the 
decomposition  of  water,  oxide  of  iron  and  hydroselenic  acid  are  gener- 
ated ;  and  while  the  former  unites  with  muriatic  acid,  the  latter  escapes 
in  the  form  of  gas. 

SELENIUM    AND    SULPHUR. 

Sulphuret  of  Selenium. — Atom.  Numb.  64 — Symb.  14 
S+Se. 

When  sulphuretted  hydrogen  gas  is  conducted  into  a  solution  of  se- 
lenic  acid,  an  orange-coloured  precipitate  subsides,  which  is  a  sul- 
phuret  of  selenium.  It  fuses  at  a  heat  a  little  above  212O  F.  and  at  a 
still  higher  temperature  may  be  sublimed  without  change.  In  the  open 
air  it  takes  fire  when  heated,  and  sulphurous,  selenious,  and  selenic 
acids  are  the  products  of  its  combustion.  The  alkalies  and  alkaline 
hydrosulphurets  dissolve  it.  Nitric  acid  acts  upon  it  with  difficulty  ; 
but  nitro-muriatic  acid  converts  it  into  sulphuric  and  selenic  acids. — 
Ann.  of  Phil.  xiv.  Berzelivs,  ii.  415. 

SELENIUM  AND  PHOSPHORUS. 

PhospJturet  of  Selenium. 

The  phosphuret  of  selenium  may  be  prepared  in  the  same  manner 
as  the  sulphuret  of  phosphorus  ;  but  as  selenium  is  capable  of  uniting 
with  phosphorus  in  several  proportions,  the  compound  formed  by  fus- 
ing them  together  can  hardly  be  supposed  to  be  of  a  definite  nature. 
This  phosphuret  is  very  fusible,  sublimes  without  change  in  close  ves- 
sels, and  is  inflammable.  It  decomposes  water  gradually  when  digest- 
ed in  it,  giving  rise  to  seleniuretted  hydrogen  and  one  of  the  acids  of 
phosphorus — Ann.  of  Phil.  xiv.  Berzelius,  ii.  417. 


GENERAL  PROPERTIES  OF  METALS. 

CHAPTER  VIII. 
METALS. 


195 


GENERAL   PROPERTIES    OP   THE    METALS, 

The  metals  constitute  the  most  important  class  of  substances  with 
which  we  are  acquainted.  They  are  characterized, — by  being  all  con- 
ductors of  caloric  and  electricity, — by  appearing,  when  combined  with 
oxygen,  chlorine,  iodine,  sulphur,  or  similar  substances,  and  subjected 
to  the  action  of  galvanism,  at  the  negative  pole  of  the  battery, — by  be- 
ing quite  opaque. — by  being  good  reflectors  of  light,  and  by  possessing 
a  peculiar  lustre,  denominated  the  metallic  lustre. 

The  number  of  metals  at  present  known  to  chemists,  is  forty-two. 
Some  of  these  were  known  and  made  use  of  in  the  earliest  ages  of  the 
world,  whereas  others  were  discovered  during  the  present  century. 
The  following  table  designates  the  names  of  the  metals  and  the  date  of 
the  discovery,  so  far  as  this  is  known,  together  with  the  name  of 
the  discoverer. 


Names  of  Metals. 

1.  Gold,         ^ 

2.  Silver, 

3.  Iron, 

4.  Copper,       }> 

5.  Mercury,    I 

6.  Lead, 

7.  Tin.  j 

8.  Antimony, 

9.  Zinc, 

10.  Bismuth, 

11.  Arsenic,  ) 

12.  Cobalt,    I 

13.  Platinum, 

14.  Nickel, 

15.  Manganese, 

16.  Tungsten, 

17.  Tellurium, 

18.  Molybdenum, 

19.  Uranium, 

20.  Titanium, 

21.  Chromium, 

22.  Columbium, 

23.  Palladium,  > 

24.  Rhodium,   $ 

25.  fridium, 

26.  Osmium, 

27.  Cerium, 

28.  Potassium, 

29.  Sodium, 

30.  Barium, 

31.  Strontium, 

32.  Calcium, 


Authors  of  the  Discovery.  Date. 


Known  to  the  Ancients. 


Described  by  Basil  Valentine,  15th  cent. 

Described  by  Agricola,  in  -  1520. 

First  mentioned  by  Paracelsus,  16th  cent. 

Brandt,  in 1733. 

Wood,  Assay  Master,  Jamaica,  -        -  1741. 

Cronstedt, 1751. 

Gahn  and  Scheele,  -         -         -  1774. 

MM.  D'Elhuyart,       ....  1781. 

Muller, 1782. 

Hielm, 1782. 

Klaproth,  -        -         -        -        -        -  1789. 

Gregor,      -  ....  1791. 

Vauquelin, 1797. 

Hatchett,  ------  1802. 


Dr.  Wallaston,           ....  1803. 

Descotils  and  Smithson  Tennant,       -  1803. 

Smithson  Tennant,  -         -         -         -  1803. 

Hisinger  and  Berzelius,      •  1804. 

Sir  H.Davy, 1807. 


196     GENERAL  PROPERTIES  OF  METALS. 


Names  of  Metals. 

33.  Cadmium, 
34.  Lithium, 
35.  Silicium,        > 
36.  Zirconium,    5 
37.  Aluminum,    ) 
38.  Glucinum,      > 
39.  Yttrium,        ) 
40.  Thorium, 
41.  Magnesium, 
42.    Vanadium. 

Authors  of  the  Discovery. 
Stromeyer,         ... 

Date. 

-    1818. 

-     1818 

JBerzelius,  - 

Wbhler,     .... 
Berzelius,  -        ... 

-     1824. 

-    1828. 
-     1829. 

IQOQ 

1820. 

Metallic  Lustre. — This  property  depends  upon  the  opacity  of  the  me- 
tals, in  consequence  of  which  the  light  is  reflected  by  their  surface  more 
completely  than  it  is  from  other  bodies.  The  metals,  however,  differ  in 
their  lustre.  Platinum  possesses  it  in  the  highest  degree  ;  after  which, 
according  to  Leslie,  are  silver,  mercury,  gold,  copper,  tin  and  lead. 

Specific  gravity. — Great  specific  gravity  was  formerly  considered  as 
a  distinctive  character  of  the  metals  ;  none  being  known  previous  to 
the  decomposition  of  the  alkalies,  less  than  six  times  heavier  than  wa- 
ter. But  the  metallic  bases  of  most  of  the  alkalies  and  earth  are  light- 
er than  that  liquid.  Indeed  the  heaviest  and  the  lightest  solids  are 
now  included  in  the  list  of  metals. 

The  following  is  a  table  of  the  specific  gravity  of  the  principal  me- 
tals compared  to  water  as  1. 

1  Platinum,  -  -  21-00        9  Nickel,    -  -  -  8-27 

2  Gold,     -  -  -  19-25  10  Iron,         -  -  -  7-78 

3  Mercury,  -  -  13-56  11  Tin,         -  -  -  7-29 

4  Lead,      -  -  -  11-35  12  Zinc,       -  -  -  7-00 

5  Silrer,    -  -  -  10-47  13  Manganese,  -  -  6-85 

6  Bismuth,  -  -  9-82  14  Antimony,  -  -  6-70 

7  Copper,  -  -  8*89  15  Sodium,  -  -  -  0-972 

8  Cobalt,  -  -  -  8-53  16  Potassium,  -  -  0-865 

Malleability. — Metals  are  said  to  be  7nalleable,  which  admit  of  being 
beaten  into  thin  plates  or  leaves  by  the  hammer.  If  when  subjected  to 
the  process  of  the  hammering,  they  break,  they  are  said  to  be  brittle. 

Malleability  is  one  of  the  most  useful  properties  of  the  metals.  It 
belongs  to  the  following,  in  the  order  in  which  they  are  arranged  : 

1  Gold,  5  Cadmium,  9  Iron, 

2  Silver,  6  Platinum,  10  Nickel, 

3  Copper,  7  Lead,  11  Palladium, 

4  Tin,  8  Zinc,  12  Potassium. 

Sodium  and  frozen  mercury  are  also  malleable. 

Gold  surpasses  all  metals  in  malleability.  When  perfectly  pure  it 
can  be  beaten  into  leaves — not  more  than  the  1-282, OOOths  of  an  inch 
in  thickness.  A  grain  of  it  can  be  beaten  out  into  so  fine  a  leaf  as  to 
cover  50  square  inches  of  surface  and  contain  two  millions  of  visible 
points  ;  but  the  gold  which  covers  the  silver- wire  used  in  making  gold 
lace,  is  spread  over  a  surface  twelve  times  as  great. 

The  leaves  of  gold  are  so  thin,  that  if  formed  into  a  book,  1,500 
would  occupy  only  the  space  of  a  single  leaf  of  common  paper;  and 
an  octavo  volume  of  an  inch  thick,  would  have  about  as  many  pages 


GENERAL  PROPERTIES  OF  METALS.      197 

as  the  books  of  a  well  stocked  ordinary  library  containing  1,500  vol- 
umes of  400  pages  in  each. — Arnott. 

Ductility. — Metals  are  said  to  be  ductile,  when  they  possess  the 
property  of  being  drawn  out  into  wires.  The  only  ones  which  are 
remarkable  in  this  respect,  are  gold,  silver,  platinum,  iron  and  cop- 
per, though  some  others  possess  ductility  in  an  inferior  degree.  Dr. 
Wollaston  devised  a  method  by  which  gold-wire  may  be  obtained  so 
fine,  that  its  diameter  shall  be  only  l-5000ths  of  an  inch,  and  that  550 
feet  are  required  to  weigh  one  grain.  He  obtained  a  platinum  wire  so 
small  that  its  diameter  did  not  exceed  l-30,000ths  of  an  inch.  [Phil. 
Trans.  1813.]  It  is  somewhat  surprizing  that  the  ductility  and  mallea- 
bility of  the  same  rnetals,  are  not  always  in  proportion  to  one  another. 
Iron,  for  example,  cannot  be  made  into  fine  leaves,  but  it  may  be  drawn 
into  very  small  wires. 

Tenacity. — By  tenacity  is  meant  the  power  of  supporting  weight  with- 
out breaking.  According  to  the  experiments  of  Guyton-Morveau,  iron 
in  point  of  tenacity,  surpasses  all  the  other  metals.  The  results  which 
he  gives  in  the  Ann.  de  Chim.,  are  as  follows  : 

The  diameter  of  each  wire  was  0-787 ths  of  a  line. 

Iron  wire  supports,          ....  549-25  pounds. 

Copper, -  302-278 

Platinum,                  274-320 

Silver,     -------  187-137 

Gold, 150-753 

Zinc, 109-540 

Tin, 34-630 

Lead, •-  27-621 

Hardness. — The  metals  differ  considerably  from  each  other  in  hard- 
ness. Among  those  which  are  most  hard,  may  be  ranked  titanium, 
manganese,  iron,  nickel,  copper,  zinc  and  palladium.  Gold,  silver 
and  platinum,  are  softer  than  these  ;  lead  is  still  softer,  and  potassium 
and  sodium  yield  to  the  pressure  of  the  fingers. 

Structure. — Many  of  the  metals  have  a  crystalline  structure,  though 
this  is  by  no  means  common  to  all.  Crystals  may  be  most  easily  pro- 
cured from  those  metals  which  fuse  at  a  low  temperature.  Bismuth 
offers  the  finest  illustration,  as  it  affords  when  fused  and  treated  in  the 
manner  described  when  noticing  the  crystallization  of  sulphur,  beau- 
tiful and  regular  cubic  crystals.  Arsenic  crystallizes  in  regular  tetra- 
hedrons, and  titanium  in  long  slender  filaments  or  prisms.  It  may  be 
also  observed  that  some  metals,  as  gold,  copper,  and  silver,  occur  na- 
turally in  the  form  of  crystals. 

Native  state  of  Metals. — When  metals  occur  in  the  earth  in  a  state  of 
purity,  they  are  called  Native.  To  this  class,  however,  belong  only 
those  which  have  a  feeble  attraction  for  oxygen,  as  gold,  silver,  platin- 
um, mercury,  &c.  Commonly  they  are,  as  it  is  termed,  mineralized,  by 
oxygen,  sulphur,  or  arsenic  ;  and  they  are  sometimes  also  found  in 
the  state  of  salts.  From  these  compounds  the  pure  metal  is  extracted 
by  various  processes,  which,  when  conducted  on  a  large  scale,  consti- 
tute the  branch  of  chemistry  denominated  metallurgy.  But  the  process- 
es of  determining  the  purity  of  metals  and  other  mineral  substances 
by  experiments  made  in  a  small  way,  is  sometimes  termed  the  art  of 
assaying. 


198     GENERAL  PROPERTIES  OF  METALS. 

Action  of  heat. — The  metals  are  all  susceptible  effusion  by  heat,  but 
the  temperatures  at  which  they  liquify  are  very  various.  Mercury  is 
fluid  at  common  temperatures,  and  requires  to  be  cooled  to — 39  -  F.  be- 
fore it  congeals.  Potassium  melts  at  136°  F.,  and  sodium  at  200°; 
tin  at  430 J;  lead  at  500°;  and  zinc  at  about  700°.  Silver,  gold  and 
copper  require  a  bright  cherry  red  heat ;  iron,  nickel  and  cobalt,  a  white 
heat ;  manganese  and  palladium,  an  intense  white  heat.  Molybden- 
um, uranium,  tungsten  and  chromium  are  only  imperfectly  agglutina- 
ted at  the  highest  temperatures  of  our  furnaces  ;  and  titanium,  cerium, 
osmium,  iridium,  rhodium,  platinum  and  columbium  require  the  in- 
tense heat  of  the  oxy hydrogen  blow-pipe  or  that  of  the  Voltaic  elec- 
tricity. 

The  metals  also  differ  greatly  in  their  volatility.  Mercury,  cadmium, 
arsenic,  tellurium,  potassium,  sodium  and  zinc  are  volatile  at  a  red 
heat  and  may  be  easily  distilled  in  close  vessels.  But  many  others  may 
be  exposed  to  the  most  intense  heat  of  a  wind  furnace  without  being 
changed  into  vapour.  It  is  probable,  however,  that  all  of  them  could 
be  converted  into  vapour  if  raised  to  sufficiently  high  temperatures,  as 
gold  and  platinum,  which  are  among  the  most  fixed,  evaporate  when 
exposed  to  the  intense  heat  of  the  focus  of  a  burning  lens. 

Action  of  the  Electric  Fluids. — The  metals  are  excellent  conductors  of 
electricity,  surpassing  in  this  respect  all  other  bodies.  When  their 
surface  is  sufficiently  extensive  to  carry  off  the  fluid,  they  undergo  no 
change ;  but  when  the  contrary  is  the  case,  the  fluid  penetrates  the 
interior,  heats,  and  in  some  instances  melts  and  volatilizes  them.  Such 
is  the  effect  produced  by  the  discharge  of  a  powerful  galvanic  or  Ley- 
den  battery  upon  very  fine  wires,  or  thin  plates  of  any  metal,  and  this 
is  more  apparent  if  the  experiment  be  performed  in  contact  with  air, 
when  the  combustion  is  more  or  less  vivid,  and  the  flame  assumes  dif- 
ferent colours.  For  example,  iron  burns  with  a  very  vivid  white  light, 
zinc  with  a  whitish  or  yellowish  white  light,  silver  with  a  green,  &c. 

Action  of  Oxygen  Gas. — Oxygen  gas,  in  a  dry  state  is  absorbed  by 
but  few  of  the  metals  at  ordinary  temperatures.  Among  these  are  po- 
tassium, barium,  lithium,  strontium,  calcium,  and  the  bases  of  the 
earths.  But  at  an  elevated  temperature,  it  acts  upon  almost  all  the 
metals,  except  platinum,  silver,  gold,  palladium,  iridium  and  rhodium. 
In  some  cases  the  union  of  the  metals  with  oxygen  is  so  rapid  as  to 
give  rise  to  all  the  phenomena  of  real  combustion.  Zinc  burns  with 
a  brilliant  flame  when  heated  to  full  redness  in  the  open  air,  and  iron 
emits  vivid  scintillations  on  being  inflamed  in  an  atmosphere  of  oxygen 
gas.  The  same  will  apply  to  tin,  cadmium,  arsenic,  antimony,  tellu- 
rium and  bismuth ;  although  the  combustion  of  tin,  antimony,  and 
bismuth,  is  the  most  feeble. 

The  product  either  of  a  slow  or  rapid  oxidation  of  a  metal,  when 
heated  in  the  air,  has  an  earthy  appearance,  and  was  termed  a  calx 
by  the  older  chemists,  the  process  of  forming  it  being  called  calcina- 
tion. 

There  are  other  processes  sometimes  employed  for  oxidating  the 
metals,  as  by  deflagration,"  that  is  by  mixing  them  with  nitrate  or 
chlorate  of  potassa,  and  projecting  the  mixture  into  a  red  hot  crucible, 
or  by  digestion  in  nitric  or  nitro-muriatic  acid. 

Some  metals  combine  with  oxygen  only  in  one  proportion  ;  but  the 
greater  number  of  them  combine  with  it  in  two  or  three  proportions. 
The  resulting  compounds  are  either  oxides  or  acids.  With  the  excep- 
tion of  arsenic,  the  metals  all  produce  oxides  by  combination  with 


GENERAL   PROPERTIES   OF   METALS.  199 

oxygen.  But  many  of  them  which,  when  combined  with  one  atom  of 
oxygen,  produce  oxides,  form  acids  when  combined  with  two  or  three 
atoms  of  oxygen.  This  occurs  in  the  case  of  chromium,  tungsten, 
molybdenum  and  vanadium. 

When  a  metallic  oxide  is  deprived  of  its  oxygen  and  brought  to  the 
metallic  state,  it  is  said  to  be  reduced,  and  the  operation  itself  is  called 
reduction.  This  reduction  may  be  effected  in  several  ways,  viz. 

1.  By  heat  alone. — The  oxides  of  gold,   silver,  mercury  and  plati- 
num, may  be  decomposed  by  subjecting  them  to  a  red  heat,  when  the 
oxygen  escapes  in  the  form  of  gas. 

2.  By  the  combined  action  of  heat  and  combustible  matter. — The 
reduction  is  effected  in  this  case  by  the  superior  attraction  of  the  com- 
bustible matter  for  oxygen.     Thus  when  oxide  of  lead  is  heated  with 
charcoal,  carbonic  acid  gas  is  evolved  and  metallic  lead  obtained. — 
Upon  the  same  principle  a  current  of  hydrogen  gas   passed  over  the 
oxides  of  copper  or  iron  heated  to  redness  in  a  porcelain  tube,   causes 
the  reduction  of  the  metal,  while  water  is  at  the  same  time  formed. 
The  metals  also  are  sometimes  employed  for  the  same  purpose,  and  it 
sometimes  happens  that  a  metal  which  at  a  low  temperature  decom- 
poses a  metallic  oxide,  may  have  its  oxide  decomposed  by  that  metal 
at  a  higher  temperature.     Thus  oxide  of  iron  is  reduced  by  potassium 
at  a  very  low  temperature  ;  while  potassa  is  reduced  by  iron  when  the 
heat  is  very  intense. 

3.  By  the  Voltaic  battery. — This  in  some  cases  effects  the  reduction 
of  an  oxide  which  resists  the  preceding  agents  :  as  in  the  case  of  ba- 
ryta and  strontia. 

4.  By  the  action  of  various  agents  on  metallic  solutions. — A  neutral 
solution  of  gold  when  exposed  to  the  sun's  rays  has  a  film  of  gold 
formed  on  the  side  turned  to  the  light,  which  gradually  increases  in 
thickness.     Phosphorous  acid  when  added  to  a  liquid  containing  oxide 
of  mercury,  deprives  the  oxide  of  its  oxygen,   metallic  mercury  sub- 
sides, and  phosphoric  acid  is  generated.     Certain  metals  also  introdu- 
ced in  the  metallic  state  into  saline  solutions  of  some  others,   deprive 
the  latter  of  their  acid  and  oxygen  and  precipitate  them  in  a  metallic 
state.*     Thus  mercury  added  to  a  solution  of  nitrate  of  silver  throws 
down  metallic  silver,  and  oxide  of  mercury  is  dissolved  by  the  nitric 
acid.     In  these  cases  the  reduced  metal  is  usually  obtained  in  the  state 
of  fine  powder  or  cohering  together  in  a  porous  mass.     Occasionally, 
however,  it  is  met  with  in  a  solid  malleable  state,  and  even  in»the  form 
of  regular  crystals.     Thus  it  is  stated  that  in  the  copper  pits  of  An- 
glesea,  where  iron  is  thrown  in  to  reduce  the  copper  from  its  solutions, 
malleable  and  crystallized  copper  has  often  been  obtained.     And  it  has 
been  recently  ascertained  by  Wach  that  whenever  the  process  proceeds 
with  sufficient  slowness,  the  metal  is  deposited  in  this  form.     A  very 
convenient  method   of  accomplishing  this  object  is   to   sew  up   the 
metal  in  two  or  three  folds  of  bladder,  and  so  immerse  it  in  the  solu- 

*  [n  a  series  of  experiments  which  I  performed  for  the  purpose  of  ascer- 
taining1 whether  the  process  of  crystallization  was  at  all  influenced  by  mag- 
netism, in  which  nothing  was  observed  to  confirm  the  views  of  Murray,  I 
found  that  the  process  of  metallic  precipitation  was  greatly  influenced  by  solar 
light.  Glass  tubes  bent  in  the  form  of  the  letter  V,  and  containing  solution  of 
nitrate  of  silver,  and  metallic  mercury,  always  had  the  largest  and  most  nu* 
merous  blades  of  silver  in  that  leg  of  the  tube  which  was  turned  to  the  light. 


200      GENERAL  PROPERTIES  OF  METALS. 

tion  to  be  precipitated,  when  the  metal  will  be  deposited  on  the  outer 
surface  in  a  massive  state. — Johnston's  Report. 

The  action  of  atmospheric  air  upon  the  metals  is  analogous,  though 
less  powerful  than  that  of  oxygen. 

Those  metals  which  are  speedily  acted  upon  by  common  air  and 
oxygen,  are  also  generally  susceptible  of  decomposing  water ;  some 
of  them  rapidly,  others  slowly.  There  are  some  metals  which  are  not 
acted  upon  by  air  deprived  of  moisture,  nor  by  water  deprived  of  air ; 
but  moist  air,  or  water  containing  air,  effects  their  oxidizement  ;  this 
appears  to  be  the  case  with  iron. — Hall,  in  Brande's  Jour.  vii.  55. 

Water  combines  with  some  of  the  metallic  oxides,  and  produces 
hydrated  oxides,  or  metallic  hydrates.  In  these,  the  relative  proportion 
of  water  is  definite.  Some  are  easily  decomposed  by  heat,  as  hydrate 
of  copper ;  others  retain  water  even  when  heated  to  redness,  as  hy- 
drate of  potassa. 

Every  acid,  with  few  exceptions,  is  capable  of  uniting  with  each  of 
the  metallic  oxides,  and  of  forming  compounds,  in  which  the  separate 
qualities  of  the  component  principles  are  no  longer  apparent,  and  are 
hence  called  neutral  salts. 

Ammonia  also  combines  with  several  of  the  metallic  oxides,  forming 
what  are  called  Ammoniurets.  Some  of  these  are  crystalline  com- 
pounds, and  those  formed  by  the  union  of  ammonia  with  the  oxides  of 
gold,  silver  and  platinum,  detonate  when  heated. 

Action  of  Chlorine. — Chlorine  has  a  powerful  attraction  for  metallic 
substances.  It  combines  readily  with  many  of  the  metals  at  common 
temperatures,  and  in  some  cases  this  combination  is  attended  with  the 
evolution  of  light.  Thus  when  powdered  zinc,  antimony  or  arsenic, 
is  thrown  into  a  vessel  of  chlorine  gas,  the  metal  is  instantly  inflamed. 
Indeed  the  affinity  of  chlorine  for  the  metals  is  even  superior  to  that 
of  oxygen  ;  for  if  chlorine  gas  be  brought  into  contact  with  lime,  mag- 
nesia, baryta,  strontia  or  potassa,  at  a  red  heat,  oxygen  is  liberared, 
and  a  chloride  of  the  metal  is  formed.  The  elements  of  these  com- 
pounds are  so  strongly  united,  that  no  temperature  hitherto  tried  can 
separate  them. 

Although  the  metallic  chlorides  may,  in  most  cases,  be  formed  by 
the  direct  action  of  chlorine  upon  the  metals,  they  are  perhaps  more 
generally  obtained  by  evaporating  a  solution  of  the  muriate  of  a  me- 
tallic oxide  to  dryness,  and  applying  heat  until  all  the  water  is  driv- 
en off. 

When  a  true  metallic  chloride  is  dissolved  in  water,  there  are  two 
views  which  may  be  taken  of  the  changes  that  occur.  Either  the 
chloride  may  dissolve  as  such  in  water,  or  a  decomposition  of  that  fluid 
may  ensue, — the  chlorine  seizing  the  hydrogen  and  forming  muriatic 
acid,  while  the  metal  may  compose  with  the  oxygen  of  the  water  an 
oxide  capable  of  saturating  the  newly  formed  acid.  In  this  way,  a 
chloride  may  be  converted,  by  the  action  of  water,  into  a  true  muriate. 
The  latter  appears  to  be  the  most  correct  view,  especially  in  those  ca- 
ses where  the  chloride  contains  a  metal,  which,  per  se,  decomposes 
water  ;  as  potassium,  sodium,  &c.  On  this  subject  see  Jinn,  of  Phil. 
xvii.;  where  the  opinions  entertained  by  different  chemists  regarding 
the  action  of  the  chlorides  on  water,  have  been  collected  together  by 
Mr.  Richard  Phillips  ;  and  who  has  adduced  satisfactory  evidence,  that, 
in  many  instances,  chlorides,  by  solution  in  water,  are  converted  into 
muriates. 

The  same  course  of  reasoning  will  apply  to  the  metallic  iodides,  bro- 
mides and  fluorides. 


GENERAL  PROPERTIES  OF  METALS.      201 

Chlorine,  in  a  dry  state,  does  not  unite  with  the  pure  oxides  of  the 
metals  ;  but  if  these  last  contain  water,  they  absorb  variable  propor- 
tions of  it.  These  compounds,  however,  possess  very  little  perma- 
nency, and  none  of  them  can  be  heated  to  redness  without  decompo- 
sition. 

Action  of  Bromine — The  affinity  of  bromine  for  metallic  substances 
is  intermediate  between  chlorine  and  iodine  ;  for  while  chlorine  disen- 
gages bromine  from  its  combination  with  metals,  the  metallic  iodides 
are  decomposed  by  bromine.  The  bromides  are  formed  in  the  same 
manner  as  the  chlorides  ;  that  is  by  the  action  of  bromine  upon  the 
metals,  or  by  evaporating  solutions  of  metallic  oxides  in  hydrobromic 
acid  to  dryness. 

Action  of  Iodine. — Iodine  has  a  strong  attraction  for  the  metals,  and 
most  of  the  compounds  which  it  forms  with  them,  can  sustain  a  red 
heat,  in  close  vessels,  without  decomposition.  It  is,  however,  inferior 
in  the  force  of  its  affinity  to  either  oxygen  or  chlorine.  Chlorine  when 
brought  into  contact  with  the  iodides  at  high  temperatures,  effects 
their  decomposition  in  the  same  manner  as  it  does  that  of  the  oxides. 
Iodine  separates  oxygen  only  from  potassa,  soda,  protoxide  of  lead, 
and  the  oxide  of  bismuth,  when  heated  to  redness.  In  all  other  cases 
the  iodides  are  decomposed  by  exposure  to  oxygen  gas,  at  the  temper- 
ature of  ignition. 

According  to  Gay  Lussac,  when  the  vapour  of  iodine  is  conducted 
over  red  hot  lime,  baryta  or  strontia,  oxygen  is  not  disengaged,  but  an 
iodide  of  these  oxides  is  formed.  If  this  be  correct,  it  differs  in  this 
respect  from  chlorine.  Iodine,  however,  is  allowed  not  to  combine 
with  any  other  oxide  under  the  same  circumstances. 

Action  of  Fluorine. — As  this  substance  has  not  hitherto  been  obtain- 
ed in  a  separate  state,  we  are  unacquainted  with  the  nature  of  its 
action  on  the  metals.  There  is,  however,  every  reason  to  suppose 
that  the  compounds  obtained  by  the  evaporation  of  certain  solutions  of 
metallic  oxides  in  hydrofluoric  acid,  are  in  reality  fluorides  of  the 
metals. 

Action  of  Hydrogen. — Hydrogen  combines  with  few  metals.  The 
only  compounds,  at  present  known,  are  those  of  potassium,  zinc,  ar- 
senic and  tellurium.  These  are  either  solid  or  gaseous.  They  are 
generally  obtained  by  liberating  hydrogen  in  contact  with  the  metals. 

Action  of  Nitrogen. — Two  compounds  of  nitrogen  with  metals  are 
now  known  to  exist,  viz.  the  nitrurets  of  potassium  and  of  sodium. 
These  are  obtained  by  treating  the  metals  with  ammoniacal  gas. — 
Tkenard,  ii.  428. 

Action  of  Sulphur. — There  are  but  few  metals  which  are  incapable 
of  combination  with  sulphur.  These  sulphurets,  as  they  are  termed, 
are  often  found  native,  and  appear  to  have  been  known  in  the  earliest 
ages  of  the  world.  They  have,  therefore,  been  studied  with  great 
care  by  many  chemists. 

In  general,  metals  form  the  same  number  of  sulphurets  as  of  oxides 
and  chlorides,  and  the  same  law  of  composition  applies  to  them. 
Thus  a  proto-sulphuret  consists  of  one  atom  of  sulphur  and  one  atom 
of  the  metal  ;  a  deuto-sulphuret  of  two  atoms  of  sulphur  and  one  of 
the  rnetal,  &c. 

All  the  metallic  sulphurets  are  solid  and  inodorous.  All,  especially 
the  artificial  ones,  are  brittle,  even  though  the  metals  which  enter  in- 
to their  composition  are  ductile.  All  are  insipid,  except  those  of  the 


202  GENERAL    P-ROPERTIES   OF  METALS. 

four  first  classes.  Some,  as  the  sulphurets  of  iron,  lead,  antimony, 
&c.  have  a  metallic  lustre  ;  others,  as  the  sulphuret  of  mercury,  are 
destitute  of  it.  Most  of  them  are  susceptible  of  crystallization.  Their 
specific  gravity  is  always  less  than  that  of  the  metals  which  they  con- 
tain, unless  indeed  the  metal  itself  is  lighter  than  sulphur,  as  potassi- 
um and  sodium. 

In  those  cases  where  the  metal  itself  possesses  the  power  of  de- 
composing water  at  ordinary  temperatures,  the  sulphuret  of  the  metal 
at  this  same  temperature,  possesses  a  similar  property.  A  portion  of 
gaseous  sulphuretted  hydrogen  is  at  the  same  time  liberated  and  a  hy- 
drosulphuretted  oxide  remains.  This  takes  place  with  the  sulphurets 
of  sodium,  potassium,  &c. 

An  opinion  was  formerly  quite  prevalent  among  chemists  that  many 
of  the  metallic  sulphurets  were  compounds  of  sulphur  and  a  metallic 
oxide.  This  was  supposed  to  be  particularly  the  case  with  the  fixed 
alkalies  and  alkaline  earths.  The  more  recent  investigations  of  Ber- 
thier  and  Berzelius,  however,  have  demonstrated  that  the  metallic 
bases  of  these  agree  with  the  common  metals  in  their  disposition  to 
unite  with  sulphur.  It  is  now  certain  that  whether  a  sulphate  be  de- 
composed by  hydrogen  or  charcoal,  or  sulphur  ignited  with  an  alkali 
or  alkaline  earth,  a  metallic  sulphuret  is  always  the  product.  It  is  al- 
most equally  certain  that  there  are  no  definite  compounds  of  sulphur 
and  the  metallic  oxides. 

The  metallic  sulphurets  may  be  obtained  in  one  or  other  of  the  fol- 
lowing ways. 

1.  By  heating  the  metal  in  combination  with  sulphur  in  a  covered 
crucible. 

2.  By  mixing  sulphur  with  the  oxide  of  a  metal,  and  exposing  the 
mixture  to  heat. 

3.  By   depriving  the  neutral  sulphates  of  the  oxygen  which  they 
contain,  through  the  agency  of  heat  and  combustible  matter. 

4.  By    the   action   of  sulphuretted   hydrogen   upon   the   metallic 
salts. 

Thenard,  Trait,  de  Chim.  i.  540.  Gay  Lussac  and  Berzelius,  Mem. 
d'Arcueil,  i. 

Action  of  Phosphorus. — The  compounds  of  phosphorus  and  the  me- 
tals have  not  yet  been  very  accurately  examined,  and  for  the  informa- 
tion we  possess  concerning  them  we  are  chiefly  indebted  to  the  re- 
searches of  Pelletier.  Phosphorus  has  heretofore  been  combined  with 
only  twenty-one  metals,  though  it  is  probable  that,  like  sulphur,  it  is 
capable  of  uniting  with  all.  Pelletier  supposed  .that  it  combines  only 
in  one  proportion  with  a  metal,  but  this  opinion  is  now  abandoned  ;  it 
is  most  probably  subject  to  the  same  laws  of  combination  as  sulphur 
and  selenium. 

All  the  metallic  phosphurets  are  solid,  inodorous,  brittle,  and  taste- 
less, except  those  of  the  metals  which  decompose  water  at  the  ordinary 
temperature,  and  give  rise  to  caustic  oxides  ;  most  of  them  are  crys- 
tallizable  and  have  a  brilliant  metallic  lustre. 

Many  of  the  metallic  phosphurets  are,  wholly  or  in  part,  decompos- 
ed by  high  temperatures,  and  those  of  the  bases  of  the  fixed  alkalies 
and  alkaline  earths  are  decomposed  by  water.  Thus  when  phosphuret 
of  potassium  is  thrown  upon  water,  protoxide  of  potassium  is  formed 


GENERAL    PR OPERTlCTfe^feiS^Btjybf .  203 

and  phosphuretted  hydrogen  is  liberated,  being  known  by  its  inflam- 
mation when  coming  in  contact  with  the  air. 

None  of  the  metallic  phosphurets  have  hitherto  been  found  in  nature. 
They  may  be  artificially  prepared  in  several  ways. 

1.  By  bringing  phosphorus  either  solid  or  in  vapour,  in  contact  with 
metals  at  high  temperatures. 

2.  By  mixing  phosphate  of  lime  and  charcoal  with  the  metal  and 
exposing  the  mixture  to  heat  in  a  covered  ciucible. 

3.  By  passing  a  current  of  phosphuretted  hydrogen  through  solu- 
tions  of  certain  metallic  salts  in  water  ;  during  this  process  water  is 
formed  and  the  phosphuret  is  precipitated  in  the  form  of  flocks. 

The  remarks  which  have  been  heretofore  made,  concerning  the 
compounds  of  sulphur  and  the  metallic  oxides,  will  apply  to  phos- 
phorus. It  is  very  doubtful  whether  there  are  any  definite  com- 
pounds of  phosphorus  and  these  oxides  ; — although  it  is  asserted, 
by  some  chemists,  that  phosphurets  of  lime  and  baryta  may  be  made 
by  conducting  the  vapour  of  phosphorus  over  those  earths  at  a  red 
heat. 

Action  of  Carbon. — Most  of  the  metals*  which  have  been  reduced  by 
charcoal  retain  a  variable,  though  usually  a  very  small  quantity  of  it, 
And  contrary  to  the  idea  formerly  maintained,  definite  compounds  are 
in  this  manner  formed.  The  most  important  of  these  are  cast  iron 
and  steel,  which  will  be  particularly  noticed  under  the  head  of  iron. 

Action  of  Cyanogen.  —  Cyanogen,  as  already  stated,  (p.  180,)  has  an 
affinity  for  metallic  substances.  Few  of  the  Cyanides,  however,  have 
been  hitherto  obtained  in  a  separate  state,  excepting  those  of  potas- 
sium, mercury,  silver  and  palladium.  The  three  latter  are  readily  de- 
composed by  heat.  Cyanogen  also  unites  with  some  of  the  metallic 
oxides. 

Action  of  Boron. — There  is  but  little  known  concerning  the  boru- 
rets.  According  to  M.  Descotils,  however,  they  are  solid,  brittle,  in- 
sipid and  inodorous  ;  and  they  are  formed  by  calcining  strongly  a  mix- 
ture of  charcoal,  boracic  acid  and  filings  of  iron  or  platinum,  formed 
into  a  paste  with  oil  or  fat.  In  this  process  the  oxygen  of  the  boracic 
acid  unites  with  the  carbon,  producing  carbonic  oxide,  which  is  disen- 
gaged; at  the  same  time  the  boron  combines  with  the  iron  or  platinum, 
forming  a  boruret. 

Action  of  Selenium. — It  is  probable  that  selenium  will  unite  with 
most  of  the  metals.  The  combination  is  effected  by  bringing  selenium 
in  contact  with  metals  at  a  high  temperature,  or  by  adding  hydrosele- 
nic  acid  to  metallic  solutions.  The  seleniurets  have  a  close  resem- 
blance to  sulphurets. 

Actions  of  metals  upon  each  other. — The  union  of  a  metal  with  one 
or  more  metals,  is  termed  an  alloy  ;  and  each  alloy  is  distinguished  by 
the  name  of  the  metals  which  constitute  it.  Thus  an  alloy  of  lead  and 
tin  is  a  combination  of  lead  and  tin.  The  name  amalgam,  however, 
is  applied  to  combinations  of  mercury  with  the  metals.  Thus  when 
we  speak  of  an  amalgam  of  this  or  that  metal,  we  express  a  compound 
of  that  metal  with  mercury. 

The  study  of  the  metallic  combination  has  not  yet  received  that 
attention  which  its  importance  seems  to  demand.  It  is  probable  that 
each  metal  is  capable  of  combining  in  one  or  more  proportions  with 
every  other  metal,  though  the  number  of  alloys  at  present  known, 


204  GENERAL    PROPERTIES    OF    METALS. 

does  not  exceed  one  hundred  and  forty.  But  it  may  be  observed  that 
there  are  some  circumstances  which  will  prevent  the  number  of  these 
.compounds  from  reaching  the  limit  which  theory  may  designate. 
Among  these  may  be  ranked,  in  particular,  the  very  different  fusibili- 
ty and  volatility  of  the  metals  ;  causes  which  oppose  obstacles  to  the 
formation  of  alloys. 

Chemists  very  generally  agree  that  the  metals  unite  with  each 
other  in  every  proportion,  in  the  same  manner  as  sulphuric  acid  or 
alcohol  and  water  ;  and  that  their  combination  is  not  governed  by 
those  laws  which  apply  to  the  oxides,  acids  and  other  definite  com- 
pounds. An  opposite  opinion,  however,  has  been  maintained  by  Ber- 
zelius,  as  well  as  by  Dalton.  Potassium,  the  former  observes,  gives, 
with  mercury,  two  crystallized  compounds,  one  of  which  contains 
twice  as  much  potassium  as  the  other.  The  Arbor  Diana?  is  a  defi- 
nite compound  of  silver  and  mercury.  When  zinc  and  copper  are 
distilled  together,  a  certain  quantity  of  zinc  comes  over,  but  the  rest 
cannot  be  raised  by  heat.  From  a  fused  mixture  of  antimony,  iron 
and  copper  with  much  tin,  metallic  crystals  separate  on  cooling,  con- 
taining fixed  proportions  of  the  component  metals.  Indeed,  as  Mr. 
Turner  remarks,  it  is  possible  that  the  variety  of  proportions  is  rather 
apparent  than  real,  arising  from  the  mixture  of  a  few  definite  com- 
pounds with  one  another,  or  with  uncombined  metals,  an  opinion  not 
only  suggested  by  the  mode  in  which  alloys  are  prepared,  but  in  some 
measure  by  observation.  Still,  however,  the  present  state  of  our 
knowledge  does  not  warrant  us  in  considering  all  the  alloys  as  chemi- 
cal compounds. 

The  alloys  resemble  the  metals  in  most  of  their  physical  pro- 
perties. They  are  solid  at  ordinary  temperatures,  except  the  al- 
loy of  potassium  and  sodium,  and  the  amalgams  in  which  mercury 
predominates ;  they  are  opaque  ;  possess  the  metallic  lustre  ;  are 
good  conductors  of  electricity  and  caloric ;  and  are  more  or  less 
crystalline  in  structure.  They  often  differ  in  some  respects  from  the 
metals  of  which  they  are  composed.  The  colour  of  an  alloy  is  some- 
times different  from  that  of  its  constituents,  of  which  brass  is  a  re- 
markable example.  The  hardness  of  a  metal  is  in  general  increased 
by  being  alloyed,  and  for  this  reason  its  elasticity  and  sonorousness 
are  frequently  improved.  The  malleability  and  ductility  of  metals,  on 
the  contrary,  are  usually  impaired  by  combination.  Alloys  formed  of 
two  brittle  metals  are  always  brittle  ;  and  an  alloy  composed  of  a 
ductile  and  a  brittle  metal  is  generally  brittle,  especially  if  the  latter 
predominate.  An  alloy  of  two  ductile  metals  is  sometimes  brittle. 

The  density  of  an  alloy  is  sometimes  less,  sometimes  greater,  than 
the  mean  density  of  the  metals  of  which  it  is  composed. 

The  fusibility  of  metals  is  greatly  increased  by  being  alloyed.  Thus 
pure  platinum,  which  cannot  be  completely  fused  in  the  most  intense 
heat  of  a  wind  furnace,  forms  a  very  fusible  alloy  with  arsenic. 

The  tendency  of  metals  to  unite  with  oxygen  is  considerably  aug- 
mented by  being  alloyed.  This  effect  is  particularly  conspicuous 
when  dense  metals  are  liquefied  by  combination  with  quicksilver,  and 
is  manifestly  owing  to  the  loss  of  their  cohesive  power.  Lead  and  tin, 
for  instance,  when  united  with  mercury,  are  soon  oxidized  by  ex- 
posure to  the  atmosphere  ;  and  even  gold  and  silver  combine  with 
oxygen,  when  the  amalgams  of  those  metals  are  agitated  with  air. — 
The  oxidability  of  one  rnetal  in  an  alloy  appears  in  some  instances  to 
be  increased  in  consequence  of  a  galvanic  action.  Thus  Mr.  Faraday 
observed,  that  an  alloy  of  steel  with  100th  of  its  weight  of  platinum 


GENERAL    PROPERTIES    OF    METALS.  205 

was  dissolved  with  effervesence  in  dilute  sulphuric  acid,  which  was  so 
weak  that  it  scarcely  acted  on  common  steel ; — an  effect  which  he 
ascribes  to  the  steel  in  the  alloy  being  rendered  positive  by  the  pres- 
ence of  the  platinum. — Turner. 

A  number  of  metallic  alloys  are  found  native  ;  among  these  may  be 
mentioned  those  of  arsenic,  with  bismuth,  with  antimony,  with  nickel, 
with  iron,  and  with  silver  ;  of  iron  and  nickel  ;  of  silver  and  antimo- 
ny ;  silver  and  lead  ;  nickel  and  cobalt,  besides  a  great  many  others, 
especially  those  which  are  found  in  the  mines  of  platinum  and  tellu- 
rium. 

Alloys  may  be  prepared  artificially,  by  heating  in  a  crucible  the 
metals  of  which  they  are  composed.  When  fusion  has  been  effected 
they  are  to  be  carefully  mixed,  without  which,  especially  if  the  metals 
are  of  different  specific  gravities,  the  alloy  will  not  be  homogeneous. 
If  one  or  both  the  metals  are  volatile,  care  should  be  taken  not  to  sub- 
ject the  alloy  to  too  high  heat.  A  modification  of  this  process  is  re- 
quired for  the  preparation  of  alloys  of  potassium  and  sodium,  which 
cannot  be  effected  in  contact  with  air.  For  this  purpose  we  should 
employ  a  tube  closed  at  one  end  ;  the  potassium  or  sodium  is  put  into 
the  lower  part  and  covered  with  the  metal  with  which  it  is  to  be  alloy- 
ed ;  the  tube  is  then  to  be  heated  until  both  the  metals  are  fused. 

Amalgams  are  either  liquid  or  solid;  liquid,  when  the  mercury  pre- 
dominates, and  generally  solid  when  the  quantity  of  mercury  is  less 
than  that  of  the  metal  to  which  it  is  united.  There  is,  however,  con- 
siderable variation  in  this  respect.  Thus  the  amalgam  formed  of  80 
parts  of  mercury  and  I  of  sodium  is  solid,  while  that  formed  of  15 
parts  of  mercury  and  1  of  tin  is  liquid.  In  the  liquid  state,  the  amalgams 
resemble  mercury,  except  that  they  flow  less  easily ;  in  their  solid 
state  they  are  brittle.  They  are  very  generally  of  a  white  colour. 
They  are  all  susceptible  of  crystallization,  and  of  being  formed  in 
constant  proportions.  To  effect  this  it  is  necessary  to  dissolve,  by 
heat,  a  certain  quantity  of  a  metal  in  mercury,  and  to  suffer  the  com- 
bination to  become  cold  ;  it  then  separates  into  two  portions,  the  one 
solid  and  crystallized,  the  other  liquid. 

All  the  amalgams  can  be  decomposed  by  a  red  heat.  Almost  all  the 
liquid  amalgams  which  contain  an  easily  oxidized  metal  are  decompos- 
ed by  the  contact  of  air ;  this  is  particularly  the  case  with  the  amal- 
gams of  potassium,  barium,  strontium  and  calcium. 

The  amalgams  may  be  prepared  by  bringing  mercury  in  contact 
with  the  metals  in  a  state  of  minute  division.  It  is  well  known  that 
mercury  instantly  combines  with  gold  and  assumes  a  white  colour. 
These  combinations,  however,  may  be  more  advantageously  formed  by 
the  aid  of  heat ;  indeed  the  amalgams  of  zinc  and  antimony  can  only 
be  properly  formed  by  melting  these  metals,  and  throwing  into  them 
the  metals  slightly  heated  by  little  at  a  time. 

Some  amalgams  may  also  be  formed  by  the  action  of  the  Voltaic  bat- 
tery. Thus  when  a  globule  of  mercury  is  placed  in  contact  with  the 
negative  wire,  during  the  process  of  decomposing  potassa  by  galvan- 
ism, an  amalgam  of  potassium  is  formed. 

Some  of  these  combinations  are  of  great  importance  in  the  arts. 


206  GENERAL    PROPERTIES    OF    METALS. 

CLASSIFICATION  OP  THE  METALS. 

The  study  of  the  metals  ought  not  to  be  conducted  in  an  arbitrary 
manner.  They  may  be  conveniently  divided  into  the  following  natural 
groups  or  classes,  viz  : 

CLASS  I.     Metals,  which  wheii  combined  with  oxygen  form  the  fixed  al- 
kalies. 

Potassium,  Sodium,  Lithium. 

These  metals  have  such  a  powerful  attraction  for  oxygen,  that  at 
common  temperatures  they  decompose  water  at  the  moment  of  con- 
tact, and  are  oxidized;  while  at  the  same  time,  the  hydrogen  of  the 
water  is  liberated  in  a  gaseous  form.  The  resulting  oxides  are  dis- 
tinguished by  their  causticity  and  solubility  in  water,  and  by  their  pos- 
sessing properties  which  are  denominated  alkaline. 

CLASS  II.     Metals,  which  when  combined  with  oxygen  form  alkaline 
earths. 

Barium,  Strontium,  Calcium,  Magnesium. 

These,  like  the  preceding,  decompose  water  at  ordinary  tempera- 
tures. The  resulting  oxides  are  called  Alkaline  Earths  /  because,  while 
in  their  appearance  they  resemble  the  earths,  they  are  similar  to  the 
alkalies,  in  having  a  strong  alkaline  reaction  with  test  paper,  and  in 
neutralizing  acids.  The  three  first  are  strongly  caustic,  and  baryta 
and  strontia  are  soluble  in  water  to  a  considerable  extent. 

CLASS  III.     Metals ,  which  when  combined  with  oxygen  form  earths. 

Aluminium,  Glucinum,  Yttrium, 

Zirconium,  Silicium,  Thorium. 

The  oxides  of  these  metals  constitute  the  well  known  substances 
denominated  pure  earths.  They  are  white,  and  of  an  earthy  appear- 
ance ;  in  their  ordinary  state,  are  quite  insoluble  in  water,  and  do  not 
affect  the  colour  of  litmus  or  turmeric  paper.  As  salifiable  bases,  they 
are  quite  inferior  to  the  alkaline  earths ;  and  one  of  them,  namely 
silica,  is  considered  by  some  chemists,  as  an  acid,  for  reasons  which 
will  hereafter  be  developed* 

CLASS  IV.    Metals,  which  decompose  water  only  when  tfteir  temperature 
is  raised  to  redness. 

Manganese,  Tin,  Cobalt, 

Zinc,  Cadmium, 

Iron,  Nickel, 


GENERAL,    PROPERTIES    OF    METALS.  207 

CLASS  V.  Metals,  which  do  not  decompose  water  at  any  temperature , 
and  the  oxides  of  which  are  not  reduced  to  the  metallic  state  by  the  sole  ac- 
tion of  heat. 

These  may  be  ranged  under  two  heads  : 

1.  Those  which,  when  combined  with  oxygen,  form  acids. 

Arsenic,  Tellurium,  Chromium, 

Tungsten,  Molybdenum,  Uranium, 

Vanadium,  Antimony,  Titanium. 

Columbium,  Cerium, 

2.  Those  which  do  not  form  acids  : 

Copper,  Lead,  Bismuth. 

CLASS  VI.     Metals,  the  oxides  of  which  are  decomposed  by  a  red  heat. 

Mercury,  Silver,  Gold, 

Platinum,  Palladium,  Rhodium. 

Osmium,  Iridium, 


208  POTASSIUM. 


CLASS  I. 

METALS    WHICH    WHEN    COMBINED    WITH    OXYGEN    FORM    THE 
FIXED    ALKALIES. 


SECTION  I. 
POTASSIUM. 

Atom.  Num.  39-15—  Symb.  Po—Sp.  gr.  O.  865, 

Discovered  by  Sir  H.  Davy  in  1807,  and  particularly  examined  by 
him  and  Gay  Lussac  and  Thenard. 

PROPERTIES.  Potassium  is  solid  at  ordinary  temperatures ;  at  7(P 
F.  it  is  somewhat  fluid,  though  its  fluidity  is  not  perfect,  till  it  is  heat- 
ed to  50°  F. ;  it  sublimes  at  a  red  heat  without  undergoing  any  change, 
Erovided  the  air  be  completely  excluded  ;  at  50°  it  is  ductile  and  mal- 
jable,  and  of  the  consistency  of  soft  wax  ;  at  32J  it  becomes  a  hard 
and  brittle  solid  ;  in  colour  and  lustre  itis  precisely  similar  to  mercury; 
is  a  good  conductor  of  electricity  and  caloric  ;  has  a  great  affinity  for 
oxygen  gas,  oxidizing  rapidly  when  exposed  to  air  or  by  contact  with  flu- 
ids containing  oxygen,  and  decomposing  water  with  the  disengagement 
of  heat  and  light ;  burns  when  heated  in  the  air  with  a  brilliant  white 
light  ;  it  burns  spontaneously  in  chlorine  with  intense  brilliancy. 

Potassium  has  a  great  affinity  for  oxygen. — When  exposed  to  the  air 
or  brought  into  contact  with  fluids  which  contain  oxygen,  this  metal 
is  rapidly  Oxidized.  On  this  account  it  must  be  preserved,  either  in 
glass  tubes  hermetically  sealed,  or  under  the  surface  of  liquids,  such  as 
naphtha,  of  which  oxygen  is  not  an  element. 

It  decomposes  water. — When  potassium  is  thrown  upon  the  surface  of 
water  it  decomposes  that  liquid  with  great  rapidity,  and  the  hydrogen 
gas  evolved  carrying  with  it  small  particles  of  the  metal,  takes  fire  in 
the  air,  and  communicating  the  combustion  to  the  potassium,  the 
whole  burns  with  a  kind  of  explosion,  emitting  a  red  light. 

If  a  globule  of  potassium  be  placed  on  ice,  it  instantly  burns  with  a 
bright  flame  and  a  deep  hole  is  made  in  the  ice,  filled  with  a  fluid  which 
is  found  to  be  solution  of  potassa. 

The  production  of  an  alkali  by  the  action  of  water  upon  potassium 
is  most  satisfactorily  shown  by  dropping  a  globule  of  the  metal  upon 
moistened  paper,  which  has  been  tinged  with  turmeric.  At  the  mo- 
ment when  the  globule  comes  into  contact  with  the  paper,  it  burns 
and  it  moves  rapidly,  as  if  in  search  of  moisture,  leaving  behind  it  a 
deep  reddish  brown  trace,  and  acting  upon  the  paper  exactly  like  dry 
caustic  potassa. 

Ezp.  The  following  is  an  instructive  experiment :  Take  a  piece 
of  potassium,  wrap  it  up  in  a  small  piece  of  paper,  and  introduce  it 


POTASSIUM.  209 

quickly  into  a  glass  test  tube,  inverted  in  a  small  vessel  of  infusion  of 
blue  cabbage,  the  tube  being  filled  with  the  same  liquid.  The  metal  will 
immediately  rise  to  the  top,  and  the  moment  the  water  reaches  it 
through  the  paper,  part  of  it  will  be  decomposed,  the  oxygen  combin- 
ing with  it  and  forming  potassa,  which  changes  the  blue  of  the  infusion 
to  a  green  ;  while  an  equivalent  portion  of  hydrogen  gas  is  found  in 
the  tube  and  may  be  inflamed  by  a  lighted  taper. 

But  perhaps  the  most  striking  illustration  of  the  deoxidizing  power 
of  potassium  is  exhibited  bj  its  action  on  carbonic  acid.  When  heated 
in  contact  with  that  gas,  it  takes  fire,  and  by  uniting  with  its  oxygen, 
forms  potassa,  while  the  liberated  carbon  is  deposited  in  the  form  of 
charcoal. 

PREPARATION.  This  metal  was  first  obtained  by  Sir  H.  Davy  by 
subjecting  moistened  hydrate  of  potassa  to  the  action  of  a  powerful 
voltaic  battery — the  oxygen  of  both  the  water  and  potassa  passed 
over  to  the  positive  pole,  while  the  hydrogen  of  the  former  and 
metallic  potassium  appeared  at  the  negative.  By  this  process,  how- 
ever, the  metal  is  obtained  in  small  quantity  only  ;  but  Gay  Lussac 
and  Thenard  invented  a  method  by  which  a  larger  supply  may  be  ob- 
tained. This  process  consists  in  bringing  the  fused  hydrate  of  po- 
tassa in  contact  with  turnings  of  iron  heated  to  whiteness  in  a  gun 
barrel. 

Potassium  may  also  be  prepared,  as  first  noticed  by  M.  Curaudau, 
by  mixing  dry  carbonate  of  potassa  with  half  its  weight  of  powdered 
charcoal,  and  exposing  the  mixture,  contained  in  a  gun-barrel,  or 
spheroidal  iron  bottle,  to  a  strong  heat.  An  improvement  on  both 
processes  has  been  made  by  M.  Brunner,  who  decomposes  potassa  by 
means  of  iron  and  charcoal.  From  eight  ounces  of  fused  carbonate 
of  potassa,  six  ounces  of  iron  filings,  and  two  ounces  of  charcoal, 
mixed  intimately,  and  heated  in  an  iron  bottle,  he  obtained  140  grains 
of  potassium.  Berzelius  has  observed  that  the  potassium  thus  made, 
though  fit  for  all  the  usual  purposes  to  which  it  is  applied,  contains  a 
minute  quantity  of  carbon ;  and,  therefore,  if  required  to  be  quite 
pure,  must  be  rendered  so  by  distillation  in  a  retort  of  iron  or  green 
glass.  A  modification  of  this  process  has  been  since  described  by 
Wohler,  who  effects  the  decomposition  of  the  potassa  solely  by  means 
of  charcoal.  The  material  employed  for  the  purpose  is  'carbonate  of 
potassa,  prepared  by  heating  cream  of  tartar  to  redness  in  a  covered 
crucible. 

REFERENCES.  Sir  II.  Davy^s  Bakerian  Lecture,  Phil.  Trans.  18,08, 
Repert.  of  Arts ,  Zd  ser.  xiii.  123,  175.  Gay  Lussac  and  Thenartfs  im- 
proved method,  Recherches  Phys.  Chim.  i.  74,  B  runner's  process,  Branded 
Jour.  xv.  279.  Wohlcr^  Branded  Jour.  xxii.  206.  For  descriptions  of  the 
most  approved  processes  for  obtaining  potassium,  see  also  Berzelius,  ii.  273. 
and  Henry )  i.  544.  Dr.  Gale  on  the  preparation  of  Potassium,  Sillim.  Jour. 
xix.  205. 


POTASSIUM    AND    OXYGEN. 

Potassium  unites  with  oxygen  in  two  proportions,  forming  the  jPro- 
toxide  or  Potassa,  or  Potash,  and  the  Peroxide. 


210  POTASSIUM. 

Peroxide   of  Potassium. — Atom.   Num.  47' 15 — Symb. 
0+Po. 

SYN.     Vegetable  Alkali. 

PROPERTIES.  A  white  solid,  very  caustic,  heavier  than  potassium, 
changing  vegetable  blues  to  green  ;  fusible  at  a  heat  below  redness, 
and  bears  the  highest  heat  without  decomposition ;  very  deliquescent, 
and  hence  very  soluble  in  water ;  absorbs  oxygen  at  a  high  tempe- 
rature and  passes  into  the  state  of  peroxide  ;  attracts  moisture  and  car- 
bonic acid  from  the  air,  and  is  converted  into  a  carbonate  ;  it  cannot 
then  be  wholly  deprived  of  its  water  by  the  most  intense  heat,  having 
formed  with  it  a  solid  hydrate  of  potassa. 

NATIVE  STATE.  Potassa  occurs  in  nature  as  a  constituent  of  differ- 
ent minerals  and  in  certain  organized  bodies.  It  is  found  in  considera- 
ble quantities  in  the  minerals  felspar  and  mica,  from  which,  indeed, 
Fuchs  has  proposed  to  prepare  potash  for  commercial  purposes.  It  is 
also  contained  in  the  ashes  of  vegetables,  but  in  these  cases  it  requires 
a  subsequent  process  to  render  it  pure. 

Hydrate  of  Potassa.— Atom.  Num.  58-15— Symb.  (O-j-Po) 

+CO+H) 

SYN.  Lapis  Caustlcus  Potassce.  Potassa  fusa. — Lond.  and  Edin. 
Phar. 

PROPERTIES.  Solid  at  common  temperatures  ;  fuses  at  a  heat  rath- 
er below  redness,  and  assumes  a  somewhat  crystalline  texture  on 
cooling;  highly  deliquescent,  and  requires  about  half  its  weight  of 
water  for  solution;  soluble  likewise  in  alcohol;  destroys  all  animal 
textures,  and  hence  employed  in  surgery  as  a  caustic  ;  when  in  solu- 
tion, forms  the  aqua  potassce,  of  the  Pharmacopoeias,  which  possesses 
properties  similar  to  the  hydrate. 

PREPARATION  OF  ANHYDROUS  AND  HYDROUS  POTASSA.  The  protoxide 
of  potassium  is  always  formed  when  potassium  is  put  into  water,  or 
exposed  to  dry  air  or  oxygen  gas.  By  the  first  process,  even  when  the 
solution  is  evaporated  to  dryness  and  exposed  to  a  red  heat,  it  retains 
a  portion  of  water  ;  by  the  second  it  is  anhydrous.  The  anhydrous 
oxide  may  also  be  obtained  according  to  Berzelius,  by  fusing  one  part 
of  potassium  with  1-4  of  hydrate  of  potassa  ;  the  water  of  the  hydrate 
is  decomposed,  hydrogen  gas  is  disengaged  and  2-3  parts  of  anhydrous 
potassa  are  procured. 

The  aqueous  solution  of  potassa  is  prepared  by  decomposing  car- 
bonate of  potassa  by  lime.  The  best  process  consists  in  boiling  in  a 
clean  iron  vessel,  carbonate  of  potassa,  with  half  its  weight  of  pure 
quick  lime,  in  water.  The  lye  is  strained  through  clean  linen,  con- 
centrated by  evaporation,  again  strained,  and  set  by  in  a  well  stopped 
bottle,  till  it  admits  of  being  decanted  clear  from  the  sediment.  If  the 
clear  solution  is  evaporated  to  dryness,  and  afterwards  cast  into  sticks, 
it  forms  the  potassa  fusa.  This  may  be  further  purified  by  alcohol, 
which  dissolves  only  the  pure  hydrate  of  potassa,  and  leaves  the  im- 
purities ;  the  alcohol  is  then  driven  off  by  heat. 

According  to  Dr.  Ure,  pure  potassa  for  experimental  purposes  may 
most  easily  be  obtained  by  igniting  cream  of  tartar  in  a  crucible,  dis- 


POTASSIUM.  211 

solving  the  residue  in  water,  filtering,  boiling  with  a  quantity  of  quick 
lime  ;  and  after  subsidence,  decanting  the  clear  liquid,  and  evaporating 
in  a  loosely  covered  silver  capsule  till  it  flows  like  oil,  and  then  pouring 
it  out  on  a  clean  iron  plate.  A  solid  white  cake  of  pure  hydrate  of 
potassa  is  thus  obtained,  without  the  agency  of  alcohol.  It  must 
be  immediately  broken  into  fragments,  and  kept  in  a  well  stopped 
phial. 

In  consequence  of  the  rapid  absorption  of  carbonic  acid  by  pure 
potassa  when  it  is  freely  exposed  to  the  atmosphere,  it  is  desirable  to 
filter  its  solution  in  vessels  containing  as  small  a  quantity  of  air  as 
possible.  This  object  is  attained  by  the  apparatus  contrived  by  Mr. 
Donovan. — Ann.  of  Phil.  xxvi.  115.  Turner's  Chem.  283. 

Mr.  Dalton  has  constructed  a  table  showing  the  quantity  of  real 
potassa  in  solutions  of  different  specific  gravities. — Henry's  Chem.  L 
550. 

USES.  As  potassa  absorbs  carbonic  acid  gas  rapidly  it  is  sometimes 
employed  for  withdrawing  that  substance  from  gaseous  mixtures.  It  is 
also  employed  as  a  reagent  in  detecting  the  presence  of  bodies,  and  in 
separating  them  from  each  other.  The  solid  hydrate,  owing  to  its 
strong  affinity  for  water,  is  used  for  depriving  gases  of  hygrometric 
moisture,  and  is  well  fitted  for  forming  frigorific  mixtures. 

REFERENCES.  Lowitz's  method  of  obtaining  crystallized  Potash,  perfectly 
pure,  Ann.  de  Chim.  or  Rep.  of  Arts.  Zd  ser.  x.  225.  Berthollet  on  the  same 
subject*  Rep.  of  Arts,  2d  ser.  xii.  121.  Hope  and  Philips  on  the  preparation 
of  Aqua  Potassoz,  Ann.  of  Phil.  xvii.  CO,  190  ,xviii.  30. 

Peroxide  of  Potassium. — Atom.  Num.  63-15 — Symb.  3O+Po. 

Discovered  by  Gay  Lussac  and  Thenard. 

PROPERTIES.  Of  an  orange  colour,  caustic,  changing  infusion  of 
litmus  to  green  ;  specifically  heavier  than  potassium  ;  fusible  below  a 
dull  red  heat ;  decomposed  by  the  Voltaic  battery,  but  not  by  heat ; 
when  thrown  into  water,  oxygen  gas  is  evolved,  and  it  passes  to  the 
state  of  protoxide  ;  when  fused  and  brought  into  contact  with  com- 
bustible bodies,  they  burn  vividly  in  the  excess  of  its  oxygen. 

PREPARATION.  This  compound  may  be  prepared  by  burning  potas- 
sium in  open  air,  or  by  heating  the  metal  in  a  vessel  of  oxygen  gas 
over  mercury,  or  by  exposing  nitrate  of  potassa  to  a  red  heat. 

REFERENCES.  Thenard^s  Chem.  ii.  33S.  Bridges,  in  North  Am.  Med. 
and  Swg.  Jour.  v.  241. 

POTASSIUM    AND    CHLORINE. 

Chloride  of  Potassium. — Atom.  Num.  74  6 — Symb.  Cl+Po. 

Long  known  to  chemists  under  various  names,  as  Febrifuge  salt  of 
Sylvius  ;  Regenerated  Sea  Salt,  fyc. 

PROPERTIES.  Occurs  in  cubic  crystals,  which  have  a  saline  and 
bitter  taste,  and  require  three  parts  of  water  at  60°  F.  for  solution,  and 
rather  a  less  proportion  of  boiling  water. 

PREPARATION,     When  small  pieces  of  potassium  are  introduced  into 


212  POTASSIUM. 

chlorine,  intense  inflammation  takes  place,  and  direct  combination  en- 
sues. This  chloride  is  also  procured  by  dissolving  either  hydrate  or 
carbonate  of  potassa  in  muriatic  acid,  and  evaporating  the  solution  to 
perfect  dryness. 

POTASSIUM    AND    BROMINE. 

Bromide  of  Potassium. 

PROPERTIES.  Crystallizes  in  cubes  or  in  rectangular  prisms  ;  the 
crystals  destitute  of  water,  decrepitating  when  healed,  and  entering 
into  fusion  without  suffering  any  change  ;  very  soluble  in  water,  and 
slightly  so  in  alcohol. 

PREPARATION.  Formed  by  saturating  hydrate  of  potassa  with  bro- 
mine ;  the  solution  containing  bromate  of  potassa,  and  bromide  of 
potassium,  is  evaporated  to  dryness,  and  the  residuum  heated  until  it. 
ceases  to  evolve  oxygen.  The  bromate  is  then  converted  into  bro- 
mide.— BerzdiiLS,  iii.  374. 

POTASSIUM  AND  IODINE. 

Iodide  of  Potassium. — Atom.  Num.  165*15 — Synib.  I+Po. 

PROPERTIES.  Crystallizes  in  white  cubes  ;  fuses  readily  when  heat- 
ed, and  is  volatilized  at  a  temperature  below  redness  ;  deliquesces  in  a 
moist  atmosphere,  and  is  very  soluble  in  water ;  soluble  also  in  strong 
alcohol. 

PREPARATION.  This  compound  may  be  formed  by  heating  potassi- 
um in  a  tube  of  green  glass,  with  excess  of  iodine.  It  may  also  be  ob- 
tained by  means  of  heat  from  the  iodate,  and  by  crystallization,  from 
the  hydriodate  of  potassa. 

POTASSIUM  AND    HYDROGEN. 

These  substances  unite  in  two  proportions,  the  one  gaseous,  the 
other  solid.  The  latter  contains  the  least  hydrogen. 

Hydruret  of  Potassium. 

Discovered  by  Gay  Lussac  and  Thenard. 

PROPERTIES.  A  grey  solid,  destitute  of  metallic  lustre  ;  infusible  ; 
not  inflammable  either  in  air  or  in  oxygen  gas  at  common  tempera- 
tures, but  burns  vividly  at  a  high  one  ;  totally  decomposed  when  heat- 
ed in  a  close  vessel,  the  hydrogen  being  liberated  in  the  form  of  gas, 
the  potassium  remaining  ;  when  brought  into  contact  with  heated 
mercury,  hydrogen  gas  is  evolved,  and  an  amalgam  of  potassium  and 
mercury  is  produced. 

PREPARATION.  This  compound  may  be  prepared  by  heating  potas- 
sium in  hydrogen  gas  ;  and  the  only  difficulty  consists  in  regulating 
the  heat,  for  a  high  temperature  decomposes  the  compound. 

REFERENCE.     Thenard' s  Chem.  i.  498, 


POTASSIUM.  213 

Gaseous  Hydraret  of  Potassium. 

Discovered  by  Sementini. 

PROPERTIES.  A  colourless  gas,  which,  when  recently  prepared,  in- 
flames by  the  contact  of  oxygen  gas  or  air,  at  the  ordinary  tempera- 
ture, but  at  the  end  of  a  certain  time,  loses  this  property,  because  it 
parts  with  a  portion  of  its  potassium. 

PREPARATION.  According  to  Sementini,  gaseous  hydruret  of  potas- 
sium is  formed  when  the  hydrate  of  potassa  is  subjected  to  a  very  high 
temperature  in  contact  with  iron.  In  this  case  the  oxygen  of  the  wa- 
ter and  of  the  protoxide,  combines  with  the  iron,  while  the  hydrogen 
combines  in  part  with  the  potassium. — Thenard,  i.  499. 

POTASSIUM  AND    NITROGEN. 

According  to  Thenard,  when  potassium  is  heated  in  ammoniacal  gas, 
hydrogen  gas  is  liberated,  and  a  Nitruret  of  Potassium  is  formed,  con- 
sisting of  100  parts  of  potassium,  and  11-728  of  nitrogen. — Thenard, 


POTASSIUM  AND  SULPHUR. 

Sulphuret  of  Potassium. — Atom.  Num.  55' 15 — Symb  S+Po. 

PROPERTIES.  Has  a  reddish  colour :  fuses  below  the  temperature 
of  ignition,  and  assumes  a  crystalline  texture  on  cooling;  dissolves  in 
water,  being  probably  converted  with  the  evolution  of  caloric  into  hy- 
drosulphuret  of  potassa. 

PREPARATION.  Sulphur  and  potassium  readily  unite  by  the  aid  of 
heat,  with  the  evolution  of  so  much  caloric,  that  the  mass  becomes  in- 
candescent. The  best  method,  however,  of  preparing  this  sulphuret, 
is  to  reduce  in  a  close  vessel,  sulphate  of  potassa  with  charcoal,  or  to 
heat  the  same  salt  to  redness  in  a  glass  or  porcelain  tube,  and  then 
pass  over  it  a  stream  of  hydrogen  gas. 

Besides  this  protosulphuret,  Berzelius  has  described  four  other  com- 
pounds, which  he  obtained  by  igniting  carbonate  of  potassa  with  dif- 
ferent proportions  of  sulphur.  These  are  composed  of  one  equivalent 
of  potassium  to  two,  three,  four,  and  five  equivalents  of  sulphur. 
See  Berzelius,  in  Ann.  of  Phil.  xx.  284.  Trait,  dc  C/dm.  ii.  300. 

POTASSIUM  AND  PHOSPHORUS. 

Phosphuret  of  Potassium. 

This  compound  may  be  formed  by  the  action  of  potassium  on  phos- 
phorus with  the  aid  of  a  moderate  heat.  It  is  converted  by  water  into 
potassa  and  perphosphuretted  hydrogen  gas,  which  inflames  at  the 
moment  of  its  formation. 


214  POTASSIUM. 

POTASSIUM    AND  CYANOGEN. 

Cyanide  or  Cyanuret  of  Potassium. 

Potassium  acts  with  great  energy  upon  cyanogen  ;  by  the  aid  of 
heat  it  absorbs  this  gas,  with  the  evolution  of  light.  The  compound 
thus  formed  is  of  a  yellowish  colour  ;  has  a  very  alkaline  taste  ;  de- 
composes water,  and  gives  rise  to  hydrocyanate  of  potassa. — Thenard, 
i.  473. 

The  process  given  by  Robiquet  for  procuring  this  compound,  is  to 
subject  ferrocyanate  of  potassa  for  a  considerable  time  to  heat.  Pre- 
pared in  this  manner,  it  is  proposed  as  a  substitute  for  hydrocyanic 
acid,  for  medical  purposes. — Magendie's  Formulary,  71. 

POTASSIUM    AND    THE    METALS. 

The  compounds  of  potassium  and  the  metals  are  always  solid,  ex- 
cept when  mercury  or  sodium  form  a  part  of  them,  when  they  are 
often  liquid.  They  are  white  and  generally  brittle  ;  fusible  at  a  tem- 
perature below  redness  ;  oxidized  by  exposure  to  air  ;  and  they  decom- 
pose water  when  brought  into  contact  with  it. 

These  compounds  are  obtained  by  heating  potassium  with  the  differ- 
ent metals  in  a  glass  tube,  or  better,  by  mixing  the  metals  with  about 
half  their  weight  of  carbonized  cream  of  tartar,  throwing  them  into  a 
crucible,  covering  the  mixture  with  powdered  charcoal,  luting  the 
cover  to  the  crucible,  and  calcining  for  about  two  hours. — Serullas,  Ann. 
de  Chim. 

Alloy  of  Potassium  and  Sodium. — The  alloy  consisting  of  10  parts  of 
potassium  and  only  one  of  sodium,  is  liquid  at  0°  F.,  and  presents  the 
very  remarkable  property  of  being  lighter  than  naptha,  or  rectified 
petroleum. 

Alloy  of  Potassium  and  Bismuth. — This  may  be  obtained  by  calcin- 
ing an  intimate  mixture  of  60  parts  of  carbonized  cream  of  tartar,  and 
120  parts  of  bismuth,  in  the  manner  before  described.  This  alloy, 
rich  in  potassium,  scintillates  when  cut  with  the  scissors,  melts  and 
inflames  when  bruised,  and  decomposes  water.  A  portion  of  common 
charcoal  added  to  it,  converts  it,  according  to  Serullas,  into  a  pyro- 
phorus,  which,  when  brought  into  contact  with  water,  inflames,  and 
produces  slight  detonations. 

Alloy  of  Potassium  and  Tin. — This  may  be  formed  by  mixing  togeth- 
er 60  parts  of  tartar,  8  of  lampblack,  and  100  of  oxide  of  tin.  If  the 
quantity  of  carbon  is  doubled,  a  true  pyrophorus  is  produced. 

Amalgam  of  Potassium  and  Mercury. — When  1  part  of  potassium  and 
145  parts  of  mercury  are  heated  in  a  glass  tube  out  of  contact  of  air,  an 
amalgam  is  formed,  which  resembles  mercury  in  its  appearance  ;  it 
absorbs  oxygen  at  common  temperatures,  and  is  converted  into  pure 
mercury,  and  into  the  oxide  of  potassium. 

Amalgam  of  potassium  can  also  be  obtained  by  agitating  parcels  of 
potassium  on  a  mercurial  bath.  When  potassium  is  combined  with 
60  times  its  weight  of  mercury,  an  amalgam  is  obtained  which  is  solid, 
very  fusible,  white,  and  which  crystallizes  easily  arid  possesses  the 
same  properties  as  the  preceding. 

The  liquid  amalgam  when  placed  in  contact  with  ammonia,  or  the 
ammoniacal  salts,  produces  an  ammoniacal  hydruret  of  potassium  and 


POTASSIUM.  215 

mercury.     This  compound  is  quite  remarkable  for  its  metallic  aspect, 
its  consistency,  and  its  easy  decomposition. 

A  fact  noticed  by  Berzelius  concerning  the  action  of  amalgam  of 
potassium  upon  water,  deserves  to  be  mentioned.  It  is,  that  with 
water  alone  it  evolves  pure  hydrogen  ;  but  when  the  water  is  acid,  or 
charged  with  sal  ammoniac,  the  hydrogen  gas  disengaged  has  the  same 
odour  as  that  obtained  by  the  use  of  zinc  and  dilute  sulphuric  acid.  — 
Thenard,  i  619. 

REFERENCES.  Vauquelir),  in  Ann.  de  Chim.  et  de  Phys.  vii.  32.  Serul- 
las,  same  Work,  xxi.  197,  or  Repert.  of  Arts,  %d  ser.  xliv.  376.  Tlienard, 
Traite  de  Chim.  i.  622. 

SALTS    OF    POTASSA. 

Chlorate  of  Potassa.—  Atom.  Num.  122-6  —  Symb.  (50+CI) 


f   SYN.     Hyp  erozy  muriate  of  Potash.     Chlorate  Potassique.  —  Berzelius. 

PROPERTIES.  Colourless,  crystallizes  in  four  and  six-sided  scales 
of  a  pearly  lustre,  the  primitive  form  of  which,  according  to  Mr. 
Brooke,  is  an  oblique  rhombic  prism  ;  soluble  in  sixteen  times  its 
weight  of  water  at  60°  F.,  and  in  two  and  a  half  of  boiling  water  ;  is 
quite  anhydrous,  and  when  exposed  to  the  temperature  of  400°  or  500° 
F.  ,  undergoes  igneous  fusion,  and  on  increasing  the  heat  almost  to 
redness,  effervescence  ensues,  and  pure  oxygen  is  disengaged  ;  is  de- 
composed by  the  stronger  acids,  and  exerts  powerful  effects  on  inflam- 
mable bodies. 

It  is  decomposed  by  the  stronger  acids.  —  If  a  few  grains  of  the  salt  are 
dropped  into  a  little  concentrated  sulphuric  acid  in  a  wine  glass,  a 
strong  smell  will  arise  :  and  if  larger  quantities  of  the  materials  be 
heated  in  a  retort,  a  violent  explosion  sometimes  ensues. 
f  Muriatic  acid  disengages  chlorine  from  chlorate  of  potassa,  and  the 
addition  of  a  few  grains  of  the  salt  to  an  ounce  measure  of  the  acid, 
imparts  to  it  the  property  of  discharging  vegetable  colours. 

It  exerts  powerful  effects  on  inflammable  bodies.  —  To  one  grain  of 
the  powdered  salt  in  a  mortar,  add  about  half  a  grain  of  phosphorus. 
The  phosphorus  will  detonate,  on  the  gentlest  triture,  with  a  very 
loud  report.  The  hand  should  be  covered  with  a  glove  in  making 
this  experiment,  and  care  should  be  taken  that  the  phosphorus  does 
not  fly  into  the  eyes. 

Charcoal  or  sulphur  may  be  substituted  for  the  phosphorus  in  the 
above  experiment,  with  the  same  effects  ;  it  requires,  however,  more 
powerful  triture  ;  or  the  experiment  may  be  varied  by  wrapping  the 
rri'xed  ingredients  in  strong  paper  or  tin  foil  and  then  striking  them 
with  a  hammer. 

This  salt  may  be  substituted  for  nitre  in  the  preparation  of  gun- 
powder, but  the  mixture  of  the  ingredients  requires  great  care,  on  ac- 
count of  their  liability  to  explode  by  trituration.  When  mixed  with 
sulphur  it  often  detonates  spontaneously. 

PREPARATION.  This  salt  is  made  by  transmitting  chlorine  gas 
through  a  concentrated  solution  of  pure  potassa,  until  the  alkali  is 
completely  neutralized.  The  solution,  which,  after  being  boiled  for 
a  few  minutes,  contains  nothing  but  the  muriate  and  chlorate  of  po- 
tassa, is  gently  evaporated  till  a  pellicle  forms  upon  its  surface,  and 


216  POTASSIUM. 

is  then  allowed  to  cool.  The  greater  part  of  the  chlorate  crystallizes, 
while  the  muriate  remains  in  solution.  The  crystals,  after  being 
washed  with  cold  water,  may  be  purified  by  a  second  crystallization. 

USES.  This  salt  is  employed  in  the  preparation  of  percussion  poic- 
der,  which  is  merely  a  gunpowder  in  which  chlorate  of  potash  is  sub- 
stituted for  nitre.  A  little  of  it  is  put  into  a  thin  copper  thimble,  when 
struck  it  catches  fire  and  explodes  in  the  piece.  It  is  also  employed  in 
the  construction  of  the  pocket  lights,  now  so  generally  employed. 
For  this  purpose  the  end  of  the  match  is  dipped  into  a  paste  made  of 
chlorate  of  potassa,  sulphur,  sugar  and  gum  arabic.  These  when  per- 
fectly dry,  take  fire  by  being  dipped  into  bottles  containing  amianthus 
which  has  been  soaked  into  concentrated  sulphuric  acid. 

This  salt  is  also  used  for  medicinal  purposes  in  the  form  of  solution 
and  of  ointment. — See  Magendie's  Formulary. 

REFERENCES.  For  details  concerning  the  preparation  of  this  salt,  see 
Henry's  Chemistry ,  i.  555.  Berzelius,  iii.  403,  who  also  describes  a  Chlorite 
of  Potassa.  Fourcroy  and  VauqueUrSs  experiments  on  the  explosion  of  this 
salt. — Ann.  de  Chim.  or  Repert.  of  Arts,  1st  ser.  viii.  65.  CutbusJi's  Pyro- 
techmj,  74. 

Perchlorate  of  Potassa. — Atom.   Num.    138-6 — Symb. 

(70+Cl.)+(0+Po.) 

PROPERTIES.  Crystallizes  in  elongated  octahedrons  ;  does  not  change 
vegetable  colours  ;  requires  more  than  fifty  times  its  weight  of  water 
at  60°  F.  for  solution  ;  distilled  at  280°  F.  with  an  equal  weight  of  sul- 
phuric acid,  it  yields  perchloric  acid  :  when  heated  to  412°  F.  oxygen 
is  evolved  and  chloride  of  potassium  remains. 

PREPARATION.  This  salt  may  be  formed  by  mixing  one  part  of 
powdered  chlorate  of  potassa  with  three  of  sulphuric  acid,  and  cau- 
tiously exposing  the  mixture  to  heat  till  it  turns  white,  when  we 
obtain  a  mixture  of  bi-sulphate  and  perchlorate  of  potassa.  The  for- 
mer being  much  more  soluble  than  the  latter  in  cold  water,  their  sep- 
aration may  be  effected  by  solution  and  crystallization. 

lodate  of  Potassa.— Atom.   Num.  213-15— Symb.  (5O+I.) 

-KO+Po.) 

PROPERTIES.  Occurs  in  small  white  granular  crystals  ;  when  pro- 
jected on  hot  coals,  acts  like  saltpetre ;  difficultly  soluble  in  water  ; 
when  heated  to  redness,  oxygen  is  given  out  and  is  converted  into 
oxide  of  potassium. 

PREPARATION.  This  salt  is  easily  procured  by  agitating  iodine  with 
a  solution  of  potassa  ;  water  is  decomposed  and  gives  rise  to  a  solu- 
ble hydriodate  and  a  difficultly  soluble  iodate.  When  evaporated  to 
dryness  and  afterwards  treated  by  strong  alcohol,  the  hydriodate  is 
dissolved  and  leaves  the  iodate  in  the  form  of  crystals. 

Hydriodate  of  Potassa. — This  salt  exists  only  in  solution  ;  when  dry 
it  is  the  iodide  of  potassium.  It  is  very  soluble  in  boiling  water  and 
requires  only  two-thirds  of  its  weight  of  water  at  60°  F.  for  solution  ; 
it  is  also  soluble  in  alcohol. 


POTASSIUM.  217 

PREPARATION — This  salt  is  easily  obtained  by  neutralizing  hydriodic 
acid  with  potassa.  But  as  it  is  employed  quite  largely  for  medicinal 
purposes,  an  easier  process  may  be  adopted.  Perhaps  the  most  eligible 
of  those  which  have  been  proposed  is  to  evaporate  the  mixed  iodate  and 
hydriodate  of  potassa,  formed  by  adding  iodine  to  a  warm  solution  of 
potassa  until  the  alkali  is  neutralized,  and  exposing  the  dry  mass  in  a 
platinum  crucible  to  a  rather  low  red  heat  in  order  to  convert  the 
iodate  into  the  iodide  of  potassium.  The  fused  mass  is  then  dissolved 
out  by  water  and  crystallized.  —  Turner. 

REFERENCES.  Turner1  s  method  of  preparing  Hydriodate  of  Potassa, 
Edin.  Med.  and  Surg.  Jour.,  J/ily,  1825. 

Hydrofluate  of  Potassa. — Crystallizable  and  deliquescent  ;  its  solu- 
tion which  is  alkaline,  attacks  glass  in  a  day  or  two  and  destroys  its 
polish.  When  the  liquid  is  rendered  neutral  by  acetic  acid,  it  be- 
comes on  farther  dilution  with  water  strongly  acid,  and  vinegar  is  set 
at  liberty. 

Prepared  by  supersaturating  carbonate  of  potassa  with  hydroflu- 
oric acid,  evaporating  the  solution  to  dryness,  and  expelling  the 
excess  of  acid  by  heat. — Berzelius,  Traite  de  Chim.  iii.  377.  The, 
nard,  iii.  324. 

Bihydrnfluate  of  Potassa.  — Forms  square  tables  and  is  readily  soluble 
in  water  ;  fuses  by  heat,  giving  out  vapour  of  hydrofluoric  acid,  and 
leaving  a  portion  of  neutral  salt. 

Procured  by  adding  to  hydrofluoric  acid  a  quantity  of  potassa,  in- 
sufficient for  neutralizing  it  completely,  and  concentrating  the  solu- 
tion. By  slow  evaporation  crystals  are  obtained. — Berzelius  and  Thc- 
nard. 

These  compounds  are  probably  in  their  dry  states  Fluorides  of  Po- 
tassium. 

Nitrate  of  Potassa.— Atom.  Num.  10M5— %»&.  (5O+N) 
+  (0+Po.) 

SYN.     Saltpetre.     Nitre. 

PROPERTIES.  A  colourless  salt,  crystallizing  readily  in  six-sided 
prisms,  the  primitive  form  of  which  is  a  right  rhombic  prism  ;  [Levy, 
in  Brandes  Jour.  xv.  284]  taste  saline,  accompanied  with  an  impres- 
sion of  coolness  ;  it  requires  for  solution  seven  parts  of  water  at  60° 
F.  and  its  own  weight  of  boiling  water  ;  it  contains  no  water  of  crys- 
tallization, but  its  crystals  are  never  quite  free  from  water  lodged  me- 
chanically within  them  ;  at  616°  F.  it  undergoes  the  igneous  fusion, 
and  like  all  the  nitrates  is  decomposed  by  a  red  heat  ;  it  is  also  rapidly 
decomposed  by  sulphur,  charcoal  arid  phosphorus. 

It  is  rapidly  decomposed  by  charcoal,  sulphur,  fyc. — This  may  be 
shown,  by  mixing  two  parts  of  powdered  nilre  with  one  of  powder- 
ed charcoal,  and  setting  fire  to  the  mixture  in  an  iron  vessel  under  a 
chimney.  The  gaseous  product  of  this  combustion,  which  may  be 
collected  by  a  proper  apparatus,  is  carbonic  acid  and  nitrogen  gas. 
Part  of  the  carbonic  acid  also  remains  attached  to  the  residuary  al- 
kali and  may  be  obtained  from  it,  by  adding  a  stronger  acid.  This 
residue  was  termed  by  the  old  chemists,  Clyssus  of  Nitre ;  if  excess 


218  POTASSIUM. 

of  charcoal  be  used,  the  results  are  carbonic  oxide  and  acid,  nitrogen 
and  subcarbonate  of  potassa,  formerly  called  nitrum  Jixum  and  white 
flux. 

When  phosphorous  is  thrown  upon  nitre  and  inflamed,  a  vivid  com- 
bination ensues,  and  a  phosphate  of  potassa  is  formed.  Sulphur 
sprinkled  upon  hot  nitre  burns  and  produces  a  mixture  of  sulphate  and 
sulphite  of  potassa,  formerly  employed  in  medicine  under  the  name  of 
Glaser's  polychrest  salt.  Most  of  the  metals,  also,  when  in  filings  or 
powder,  detonate  and  burn  when  thrown  on  red  hot  nitre. 

A  mixture  of  three  parts  of  powdered  nitre,  two  of  carbonate  of 
potassa  and  one  part  of  sulphur,  dried  and  accurately  mixed  together, 
forms  the  Fulminating  Powder,  which  explodes  with  a  loud  noise  when 
laid  on  an  iron  plate  heated  below  redness. 

Gunpowder,  consists  of  a  very  intimate  mixture  of  nitre,  sulphur 
and  charcoal.  The  proportions  vary.  The  following  are  those  usu- 
ally employed. 


Common 

Shooting 

Shooting 

Miners' 

Gunpowder. 

Powder. 

Powder. 

Powder. 

Saltpetre,            75.0 

78 

76 

65 

Charcoal,             12.5 

12 

15 

15 

Sulphur,              12.5 

10 

9 

20 

The  latter  contains  the  smallest  quantity  of  saltpetre,  as  it  requires 
less  quickness  or  strength.  The  ingredients  are  perfectly  mixed,  moist- 
ened, beaten  into  a  cake  which  is  afterwards  broken  up,  granulated, 
dried,  and,  for  the  finest  powder,  polished  by  attrition.  The  violence 
of  the  explosion  of  gunpowder  depends  upon  the  sudden  production 
of  gaseous  matter,  resulting  from  the  action  of  the  combustibles  upon 
the  nitre.  Carbonic  oxide,  carbonic  acid,  nitrogen  and  sulphurous 
acid,  are  the  principal  gaseous  results,  and  the  solid  residue  consists 
of  subcarbonate  and  sulphate  of  potassa,  sulphuret  of  potassium  and 
charcoal.  — Nicholson  s  Journal,  iv. 

PREPARATION.  This  salt  is  generated  spontaneously  in  the  soil,  and 
crystallizes  upon  its  surface,  in  several  parts  of  the  world,  and  espe- 
cially in  the  East-Indies,  whence  the  greater  part  of  the  nitre  used  in 
Britain  is  derived.  It  is  also  found  abundantly  in  several  caverns  hi 
the  western  parts  of  the  United  States.  [Cleav eland' 's  Mineralogy.'] 
In  France  and  Germany,  it  is  prepared  artificially  from  a  mixture  of 
common  mould  or  porous  calcareous  earth  with  animal  and  vegetable 
remains  containing  nitrogen.  When  a  heap  of  these  materials,  pre- 
served moist  and  in  a  shaded  situation,  is  moderately  exposed  to  the  air, 
nitric  acid  is  gradually  generated,  and  unites  with  the  potassa,  lime 
and  magnesia,  which  are  commonly  present  with  the  mixture.  On 
dissolving  these  salts  in  water,  and  precipitating  the  two  earths  by  car- 
bonate of  potassa,  a  solution  is  formed,  which  yields  crystals  of  nitre 
by  evaporation.  The  nitric  acid  is  probably  generated  under  these  cir- 
cumstances by  the  nitrogen  of  the  organic  matters  combining  during 
putrefaction  with  the  oxygen  of  the  atmosphere,  a  change  which  must 
be  attributed  to  the  affinity  of  oxygen  for  nitrogen,  aided  by  that  of  ni- 
tric acid  for  alkaline  bases. — Turner. 

USES.  The  greatest  consumption  of  this  salt  is  in  the  manufacture 
of  gunpowder.  It  is  also  employed  in  the  formation  of  nitric  acid 


POTASSIUM.  219 

and  in  chemistry  as  an  oxidizing  agent.  In  the  East  Indies  it  is  used 
for  the  preparation  of  cooling  mixtures  ;  —  an  ounce  of  powdered  nitre 
dissolved  in  five  ounces  of  water  reduces  its  temperature  fifteen  de- 
grees. It  possesses  powerful  antiseptic  properties,  and  is,  therefore, 
much  employed  in  the  preservation  of  meat  and  animal  matters  in  gen- 
eral. 

ACTION  ON  THE  ANIMAL  ECONOMY.  This  salt  is  often  mistaken  for 
saline  laxatives,  especially  for  the  sulphate  of  soda,  and  has  thus  been 
the  source  of  fatal  accidents.  Cases  of  this  kind  are  related  by  Dr. 
Christison  in  his  Treatise  on  Poisons,  160. 

REFERENCES.  For  a  description  of  the  mode  of  preparing  this  salty  see 
Thenard,  Traite  de  Chirn.  iii.  252.  Thomson  on  the  effect  of  red  heat  upon 
Nitrate  of  Potassa,  First  Prin.  i.  107.  On  the  preparation  of  Gunpow- 
der —  Nicholsons  Jour,  xxiii.  277.  Dr.  Ure  on  the  composition  of  Gun. 
powder,  Journ.  of  the  Roy.  Inst.  Oct.  1830.  Gay  Ltissac's  process  for  an- 
alyzing  Gunpowder,  Ann.  de  Chim.  et  de  Phys.  xri.  434,  and  Thenard, 
iii.  269.  Longchamp  on  Nitrification,  Phil.  Mag.  and  Ann.  i.  172.  The 
article  Gunpowder  in  the  Supplement  to  the  Encyclopaedia  Britannica^ 
by  Dr.  IWCulloch.  CutbusWs  Pyrotechny.  Watson"*  s  Chemical  Essays. 

Hyposulphite  of  Potassa.  —  This  salt  is  best  formed  by  decomposing 
hydrosulphuret  of  potassa  by  sulphurous  acid.  The  salt  has  a  taste 
at  first  not  unlike  that  of  nitre,  succeeded  by  bitterness,  and  it  is  de- 
liquescent when  carefully  dried  ;  it  takes  fire  on  raising  the  heat,  and 
burns  like  tinder,  but  with  a  feeble  blue  flame  ;  it  dissolves  chloride 
of  silver,  even  when  dilute,  with  great  readiness.  —  Henry's  Chem. 
i.  570. 

Sulphite  of  Potassa.  —  A  salt,  occurring  in  rhomboidal  plates  of  a 
white  colour,  and  a  bitter  and  sulphurous  taste,  very  soluble,  and 
which  by  exposure  to  air  is  converted  into  a  sulphate.  It  is  prepared 
by  passing  sulphurous  acid  into  a  solution  of  potassa  and  evaporating 
out  of  contact  of  air. 

Hyposulphale  of  Potassa.  —  A  salt  crystallizing  in  cylindrical  prisms 
terminated  by  a  plane  perpendicular  to  their  axis.  Little,  however, 
is  known  concerning  it.  —  jinn.  Phil.  xiv.  355.  Brande'sJour.  xv.  285. 

Sulphate  of  Potassa.—  Atom.  Num.  87-15—  Symb.  (3O+S) 


SYN.     Sal  de  duobus. 

PROPERTIES.  White;  slightly  bitter  ;  crystallizes  in  short  six-sided 
prisms,  terminated  by  six-sided  pyramids  ;  it  is  destitute  of  water  of 
crystallization  and  suffers  no  change  by  exposure  to  air  ;  decrepitates 
when  heated,  and  enters  into  fusion  at  a  red  heat  ;  soluble  in  16  parts 
of  cold,  and  five  of  boiling  water  ;  is  decomposed  at  high  temperatures 
by  charcoal,  and  converted  into  sulphuret  of  potassium. 

PREPARATION  AND  NATIVE  STATE.  This  salt  is  found  native,  but  not 
abundantly,  being  principally  in  combination  with  the  acetate  and 
hydrochlorate  of  potassa,  in  woody  plants.  It  is  artificially  prepared 
by  saturating  carbonate  of  potassa  with  sulphuric  acid  ;  and  it  is  pro- 
cured abundantly  as  a  product  of  the  operation  for  preparing  nitric 
acid. 


220  POTASSIUM. 

Bisulphatc  of  Potatsa. — Atom.  Num.  127-15 — Symb.  2 
(30+S.)+(0+Po.) 

PROPERTIES.  Has  a  sour  taste,  and  a  powerful  action  upon  vegetable 
blues ;  one  part  is  soluble  in  two  of  water,  at  60°  F.  and  in  less  than 
an  equal  weight  at  212°  F. ;  insoluble  in  alcohol. 

PREPARATION.  This  salt  may  be  easily  obtained  by  dissolving  in 
hot  water  the  mass  which  remains  in  the  retort  after  distilling  nitric 
acid  from  equal  weights  of  sulphuric  acid  and  nitre  ;  or  by  digesting 
one  proportion  of  the  neutral  sulphate  with  water  containing  about  50 
parts  of  concentrated  sulphuric  acid,  and  evaporating  the  solution  — 
Thomson,  Ann.  of  Phil.  xxvi.  439. 

Ammonia  Sulphate  of  Potassa. — A  triple  salt,  crystallizing  in  bril- 
liant plates,  of  a  bitter  taste.  Formed  by  adding  ammonia  to  bisul- 
phate  of  potassa.  —  Thomson,  First  I'rin.  ii.  417. 

Hypophosphite  of  Potassa. — A  very  deliquescent  salt,  soluble  in  wa- 
ter and  in  alcohol,  nearly  in  all  proportions.  It  is  formed  by  the  di- 
rect combination  of  its  constituents. — Rose.  Ann.  de  Ch.  el  de  Ph,  July 
1828. 

Phosphite  of  Potassa. — A  neutral  salt,  not  crystallizable,  deliques- 
cent, and  very  soluble  in  water,  but  not  in  alcohol.  When  heated  a 
yellow  residue  is  left,  which,  with  acids  gives  oat  a  little  phosphuret- 
ted  hydrogen. 

Phosphate  of  Potassa. — This  salt  has  little  taste  ;  by  the  action  of 
heat  it  undergoes  igneous  fusions  ;  mixed  with  20  or  30  times  its  bulk 
of  lime  water,  it  preserves  all  its  transparency. 

It  may  be  obtained  by  neutralizing  a  solution  of  carbonate  of  po- 
tassa with  phosphoric  acid,  concentrating  the  solution  and  setting  it 
aside  for  some  days  to  crystallize. — Thomson  s  First  Prin.  ii.  256. 

Biphosphate  of  Potassa. — This  salt  has  been  very  little  examined  ; 
it  is  formed  by  dissolving  the  phosphate  in  phosphoric  acid,  and 
evaporating  till  crystals  are  obtained,  which  are  prismatic  and  very 
soluble. 

Berzelius  describes  two  other  phosphates. — Traite  de  Chim.  iii.  402. 

Carbonate  of  Potassa. -—Atom.  Num.  GQ-15—Symb.  (2O+C) 
+(0+Po) 

SYN.     Suucarlonate  of  Potash.     Salt  of  Tartar. 

PROPERTIES.  Taste  strongly  alkaline  ;  is  slightly  caustic,  and  com- 
municates a  green  to  the  blue  colour  of  the  violet ;  dissolves  in  less 
than  an  equal  weight  of  water  at  603  F. ;  deliquesces  rapidly  on  expo- 
sure to  the  air  forming  a  dense  solution  formerly  called  oil  of  Tartar  per 
ddiquium ;  it  crystallizes  with  much  difficulty  from  its  solution  ;  in- 
soluble in  pure  alcohol ;  fuses  at  a  full  red  heat  without  decompo- 
sition. 

PREPARATION.  This  salt  is  procured  in  an  impure  form  from  the 
potash  and  pearlash  of  commerce  ;  but  for  chemical  purposes  it  should 
be  prepared  from  cream  of  tartar,  the  bitartrate  of  potassa.  On  heat- 
ing this  salt  to  redness  the  tartaric  acid  is  decomposed,  and  a  pure 


POTASSIUM.  221 

carbonate  of  potassa  mixed  with  charcoal  remains.  The  carbonate  is 
then  dissolved  in  water,  and  after  filtration,  is  evaporated  to  dryness  in 
a  capsule  of  silver  or  platinum.  It  may  also  be  obtained  by  exposing 
the  bicarbonate  to  a  moderate  heat,  and  dissolving  the  resulting  salt  in 
water  ;  the  solution  is  then  filtered  to  separate  the  silicic  acid,  evapo- 
rated to  dryness,  and  kept  in  well  stopped  bottles.  The  carbonate  pre- 
pared in  this  way  is  preferred  by  Berzelius  in  chemical  analysis. 

Commercial  Potash  and  Pearlash. — If  any  vegetable  growing  in  a  soil 
not  impregnated  with  sea-salt  be  burned,  its  ashes  will  be  found  alka- 
line from  the  presence  of  carbonate  of  potassa.  By  lixiviating  the 
ashes  thus  obtained,  with  hot  or  cold  water,  the  alkaline  part  is  dis- 
solved out  and  this  solution  when  boiled  to  dryness,  leaves  behind  a 
dark  brown  saline  mass,  consisting  of  carbonate  of  potassa  with  varia- 
ble proportions  of  other  salts  and  a  minute  quantity  of  vegetable  in- 
llainrnable  matter.  In  this  state  it  is  known  in  commerce  by  the  name 
of  Potask — Calcination  at  a  moderate  heat,  burns  off  the  colouring 
particles  arid  the  salt  becomes  of  a  spongy  texture  and  beautiful  bluish 
white  tinge,  and  is  then  called  Pearlash. 

In  this  process  hot  water  dissolves  the  alkali  more  rapidly  and  com- 
pletely than  cold,  and  is  therefore  to  be  preferred  in  the  manufacture, 
and  advantage  is  also  gained  by  making  use  of  small  leach  tubs.  If 
quick  lime  be  mixed  with  the  ashes,  previous  to  lixiviation,  the  alkali 
is  rendered  more  caustic,  and  as  some  of  the  other  salts  of  potash  are 
decomposed  by  it,  the  value  of  the  resulting  mass  will  be  increased. — 
But  the  addition  of  common  salt  or  of  any  soluble  matter,  to  the  ashes, 
previous  to  lixiviation,  or  of  any  substance  to  the  lixivium  when  un- 
dergoing the  process  of  evaporation,  impairs  the  quality  of  the  potash, 
and  can  only  be  resorted  to  through  ignorance  or  for  fraudulent  pur- 
poses. 

Potash  and  Pearlash  being  so  largely  employed  in  the  arts,  it  is  fre- 
quently of  consequence  to  ascertain  the  value  of  different  samples  ; 
that  is,  to  determine  the  quantity  of  real  carbonate  of  potash  contained 
in  a  given  weight  of  impure  carbonate.  The  purity  of  pearlash  may 
in  general  be  judged  of  by  its  easy  solubility  in  water,  two  parts  of 
which  should  entirely  dissolve  one  part  of  the  salt  ;  the  residue,  if 
any,  consists  of  impurities.  But  the  purity  of  a  given  specimen  may 
be  more  correctly  determined  by  ascertaining  its  power  of  saturating  an 
acid.  Dilute  sulphuric  acid  may  be  employed  for  this  purpose.  The 
amount  of  pure  alkali  which  this  test  acid  will  saturate  having  been 
determined  by  previous  experiments,  it  is  next  to  be  ascertained  how 
much  of  this  acid  is  required  to  saturate  a  given  weight  of  impure  pot- 
ash, and  from  this  the  proportional  amount  of  pure  carbonate  may  be 
easily  ascertained  by  calculation.  Thus  if  eight  ounces  of  this  test 
acid,  neutralizes  one  ounce  of  pure  carbonate  of  potassa,  and  eight 
ounces  of  the  same  acid  require  for  their  neutralization  two  ounces  of 
common  potash,  the  latter  contains  1  ounce  of  impurities.  [For  a  de- 
scription of  a  convenient  apparatus  for  ascertaining  the  purity  of  corn- 
commercial  potash,  and  soda,  see  Faraday's  Chemical  Manipulation.] 


222 


POTASSIUM. 


The  following  table  will  exhibit  the  ingredients  of  several  specimens 
of  potash.  The  analyses  were  made  by  myself  under  the  direction  of 
a  committee  of  the  Legislature  of  New-York,  in  1832  and  3,  and  were 
confined  to  such  specimens  as  were  met  with  in  our  market. — See  As- 
sembly Journals,  1832-3. 


13 

rs"  ° 

t^    C 

o 

"o  * 

•^  «j 

M 

0) 

2  S  S 

o    ^   ei 

Is  * 

Is 

|.2.| 

*S  **">  °° 

'Q    •*-> 

i-M     a! 

O.  cd 

o  S  o 

XI         "o 

13 

rt   ^ 

3    O 

2-5^ 

^3  ^  PH 

"Q 

•-1    S 

02  Pu, 

.0  g 

JH 

1 

11-6 

7-5 

7-3 

73.6 

100 

2 

00-5 

6-3 

15- 

78.2 

100 

3 

2-4 

12-2 

1Q-8 

74.6 

100 

4 

1-6 

11  5 

10- 

76.9 

100 

5 

11-4 

4.4 

9-2 

75 

100 

6 

7-6 

10.4 

32-8 

49.2 

100 

7 

1-7 

12-5 

6'9> 

78.9 

100 

8 

2-5 

10-2 

U-l 

76.2 

100 

Of  these  specimens,  No.  1  &  7,  were  manufactured  according  to  the 
common  method.  No.  2,  3,  4r  5,  &  8,  were  made  according  to  a  me- 
thod recently  introduced  of  mixing  lime  with  the  ashes, — employing 
hot  instead  of  cold  water  in  the  lixiviation,  and  using  small  leach  tubs. 
No.  6,  was  the  result  of  a  mistaken  idea  which  was  maintained  by  some 
manufacturers,  that  the  addition  of  large  quantities  of  salt  and  lime  to 
the  lye  would  not  only  increase  the  amount  of  potash,  but  improve  its 
quality. 

REFERENCES.  Vaiiqnelirfs  Experiments  on  various  kinds  of  Potash,  fyc. 
Ann.  de  Chim*  xl.  273, or  Repertory  of  Arts,  1st  ser.  xvi.  258,  (an  important 
paper.)  On  obtaining  Potash  from  various  substances — ChaptaFs  Chem. 
ji.  78.  John  on  the  origin  of  Potash t  in  vegetables.  Ed'm.  Phil.  Jour,  iL 
394. 

Bicarbonate  of  Pot  ass  a. — Atom.  Num.  100-15—  Symb.  2. 
(20-fC)+(0+Po)+laq. 

PROPERTIES.  Crystallizes  in  eight-sided  prisms  ;  is  milder  than  the 
carbonate,  but  is  alkaline  both  to  the  taste  and  to  test  paper  ;  does  not 
deliquesce  on  exposure  to  the  air ;  it  requires  four  times  its  weight  of 
water,  at  60 3  F.  for  solution,  and  is  much  more  soluble  at  212°  F. 
but  it  parts  with  some  of  its  acid  at  that  temperature,  and  at  a  low  red 
heat  it  is  converted  into  the  carbonate. 

PREPARATION.  This  salt  is  made  by  transmitting  a  current  of  car- 
bonic acid  gas  through  a  solution  of  the  carbonate  of  potassa.  By 
slow  evaporation  the  salt  is  obtained  in  the  crystalline  form. 

Sesquicarbonate  of  Potassa,  seems  to  have  been  obtained  acci- 
dentally in  a  single  instance.  Its  constitution  is  stated  by  Dr.  Thorn- 


SODIUM.  223 

son  to  be  H  at.  carbonic  acid-f-1  potassa-f-6  water, — First  Prin.  ii. 
255. 

Sub-borate  of  Potassa. — This  salt  is  little  known.  It  may  be  formed 
by  the  direct  combination  of  liquid  hydrate  of  potassa  with  boracic 
acid. — Thenard,  ill  92. 

Selenites  of  Potussa. — Selenious  acid  is  capable  of  uniting  with  po- 
tassa in  three  different  proportions,  and  of  composing  either  a  selen- 
ite,  bi-selenite  or  quadri-selenite. — Berzclius,  Ann.  de  C/i.  and  de  Py. 
ix.  257,  and  Traite  de  C/iim.  iii.  428. 

TESTS  OF  THE  SALTS  OF  POTASSA. — 1.  A  concentrated  solution  of 
Tartaric  Acid,  added  in  excess  to  a  concentrated  solution  of  potassa 
or  any  of  its  soluble  salts,  immediately  produces  a  crystalline  pre- 
cipitate of  bitartrate  of  potassa.  When  the  solution  is  dilute,  the 
precipitate  appears  only  after  some  time.  2.  The  spirituous  solu- 
tion of  Chloride  of  Platinum,  produces  a  yellow  precipitate  of  chlo- 
ride of  potassium  and  platinum.  If  the  salt  which  is  to  be  tested  for 
potassa,  be  soluble  in  alcohol,  it  is  best  to  mix  a  spirituous  solution 
of  the  salt  with  the  spirituous  solution  of  chloride  of  platinum. — See 
Prof.  H.  Rose's  Manual  of  Analytical  Chemistry,  for  particulars  con- 
cerning the  employment  of  the  above  tests  and  several  others  of  inferior  de- 
licacy. 

SECTION  II. 

SODIUM. 

Atom.  Num.  23'3.—  Symb.  So.  Sp.  gr.  0-972 

Discovered  by  Sir.-  H.  Davy,  in  1807,  and  particularly  examined  by 
him,  and  by  Gay  Lussac  and  Thenard. — Recherckes  Phys.  Chim. 

PROPERTIES.  Solid  at  ordinary  temperatures  ;  white,  opaque,  and 
when  examined  under  a  thin  film  of  naphtha,  has  the  lustre  and  gene- 
ral appearance  of  silver  ;  is  so  soft  that  it  may  be  formed  into  leaves 
by  the  pressure  of  the  fingers,  and  possesses  the  property  of  welding ; 
fuses  at  200°  F.  and  rises  in  vapour  at  a  full  red  heat ;  it  soon  tarnish- 
es on  exposure  to  the  air,  though  less  rapidly  than  potassium  ;  when 
thrown  upon  water,  swims  upon  its  surface,  occasions  a  violent  effer- 
vescence, and  a  hissing  noise,  but  no  light  is  visible  ;  the  action  is 
stronger  with  hot  water,  and  a  few  scintillations  appear,  but  still  there 
is  no  flame  ;  in  each  case,  soda  is  generated,  owing  to  which  the  wa- 
ter acquires  an  alkaline  reaction,  and  hydrogen  gas  is  disengaged. 

Sodium  decomposes  water. — When  sodium  is  thrown  upon  pure  wa- 
ter it  rapidly  decomposes  the  water,  but  does  not  take  fire  like  potas- 
sium. This  Serrulas  ascribes  to  its  great  mobility  compared  with  that  of 
potassium.  Arid  he  says  that  if  sodium  be  placed  in  contact  with  a 
little  water,  thickened  by  gum,  it  is  then  arrested  and  enough  of  heat  is 
speedily  generated  to  set  the  sodium  on  fire.  [Ann.  de  Chim.  et  de, 
Phys.  xl.  329.]  According  to  Professor  Ducatel  sodium  inflames  with 
cold  water  when  in  contact  with,  charcoal,  and  the  product  is  water  and 
sodiuretted  hydrogen.  \_Silliman' s  Jour.  xxv.  90.]  Sodium  burns 
with  a  yellowish  flame,  while  that  of  potassium  is  reddish.  It  has  al- 
so been  recently  observed  that  when  sodium  is  pushed  altogether  under 


224  SODIUM. 

water,  the  disengagement  of  hydrogen  gas  is  then  so  sudden  and  abun- 
dant as  to  cause  a  detonation. 

PREPARATION.  Sodium  was  first  obtained  by  the  action  of  the  Vol- 
taic battery  upon  soda  ;  but  it  may  be  procured  in  much  larger  quan- 
tity by  chemical  processes,  precisely  similar  to  those  described  when 
treating  of  potassium. 

SODIUM    AND    OXYGEN. 

Chemists  are  acquainted  with  two  compounds  of  sodium  and  oxy- 
gen, viz  :  the  protoxide  or  soda,  and  the  peroxide.  Berzelius,  how- 
ever, describes  a  third,  which  he  calls  the  sub-oxide  ;  but  it  is  probable 
that  this  is  a  mere  mixture  of  the  metal  with  soda. 

Protoxide  of  Sodium,  or  Soda.  —  Atom.  Num.  31  -3  —  Symb. 
O+So. 

PROPERTIES.  Grayish-white  ;  very  caustic  ;  difficult  of  fusion  ;  spe- 
cifically heavier  than  sodium  ;  changes  vegetable  blues  to  green  ;  when 
exposed  to  the  air  it  becomes  covered  with  an  efflorescent  crust  of  car- 
bonate of  soda. 

PREPARATION.  Soda  is  obtained  by  burning  sodium  in  dry  atmos- 
pheric air.  It  is  also  formed  when  soda  is  oxidized  by  water. 

Hydrate  of  Soda.—  Atom.  Num.  40-3—  Symb.  (O+So.) 


With  water,  soda  forms  a  solid  hydrate,  easily  fusible  by  heat  ;  very 
caustic,  soluble  in  water  and  alcohol,  and  has  powerful  alkaline  pro 
perties.  It  is  prepared  from  solution  of  pure  soda,  exactly  in  the  same 
manner  as  the  corresponding  compound  of  potassa. 

Mr.  Dalton  has  constructed  a  table  showing  the  proportion  of  real 
soda,  free  from  water,  in  solutions  of  different  specific  gravities.  —  [See 
Henrys  Chem.  i.  580.] 

Peroxide  of  Sodium.—  Atom.  Num.  70-6—  Symb.  3O+2So. 

This  compound  may  be  formed  by  burning  the  metal  in  an  excess  of 
oxygen  gas.  It  is  of  a  deep  orange  colour,  very  fusible,  and  a  non-con- 
ductor of  electricity.  When  acted  on  by  water,  its  excess  of  oxy- 
gen escapes,  and  it  becomes  soda.  It  deflagrates  with  most  combusti- 
bles. —  Gay  Lussac  and  Theuard. 

SODIUM    AND    CHLORINE. 

Chloride  of  Sodium.—  Atom.  Num.  5S'75—Symb.  Cl+So. 

PROPERTIES.  A  crystalline  solid,  occurring  in  regular  cubes,  or  by 
hasty  evaporation,  in  hollow  quadrangular  pyramids,  which,  when 
the  salt  is  pure,  are  but  little  changed  by  exposure  to  the  air  ;  it  dis- 
solves in  twicp  and  a  half  its  weight  of  water  at  60°  F.,  and  is  but  lit- 
tle more  soluble  in  hot  water  ;  when  heated,  gradually  fuses  and 


SODIUM. 


225 


forms  when  cold,  a  solid  mass  ;  if  suddenly  heated,  it  decrepitates  ; 
is  not  decomposed  by  ignition  in  contact  with  i»flammable  substances, 
except  potassium  ;  is  decomposed  by  carbonate  of  potassa,  sulphuric 
and  nitric  acids,  and  when  dissolved  in  water,  is  converted  into  Muri- 
ate of  Soda. 

PREPARATION  AND  NATIVE  STATE.  This  compound  may  be  formed 
directly  by  burning  sodium  in  chlorine,  or  by  heating  it  in  muriatic 
acid  gas.  It  is  deposited  in  crystals  when  a  solution  of  muriate  of  soda 
is  evaporated  ;  for  this  salt,  like  muriate  of  potassa,  exists  only  while 
in  solution.  In  this  state  it  is  found  abundantly  as  a  natural  product 
in  sea  water,  and  in  the  various  brine  springs,  from  which  the  crystal- 
line compound  is  obtained  by  evaporation.  Chloride  of  sodium  is 
known  likewise  as  a  natural  product  under  the  name  of  rock  or  min- 
eral salt. 

Among  the  most  valuable  of  the  brine  or  salt  springs  in  the  United 
States,  are  those  of  Onondaga  County,  N.  Y.  The  manufacture  of 
salt  from  these  springs  commenced  about  the  year  1789,  but  the  quan- 
tity manufactured  has  greatly  increased  within  the  last  ten  years.  In 
1800  it  amounted  to  42,754  bushels  ;  in  1814  to  295,215  bushels  ;  in 
1823  to  608,463  bushels  ;  and  in  1833  to  1,838,646. 

According  to  an  analysis,  which  I  made,  of  the  brine  obtained  at 
Salina,  in  1825  it  contains  one-seventh  of  its  weight  of  chloride  of  so- 
dium. 1000  grains  of  this  brine  gave  156  grains  dry  saline  residuum, 
of  which  there  were  in  100  parts, 

Carbonate  of  Lime,      •  1*14 

Sulphate  of  Lime,        -        ...  2-69 

Chloride  of  Calcium,  ....  2-25 

Chloride  of  Magnesium,       -  1-54 

Chloride  of  Sodium,    -         -        -        -  92-38 

100-00 

The  results  of  my  analysis  of  the  different  varieties  of  salt  manufac- 
tured at  Salina  are  as  follows,  viz : 


o 

o  £ 

o    . 

0      . 

CD 

<D  .2 

0    S 

CD    S 

Kinds  of  Salt. 

J3   1 

12  S 

'*-<  c 

13    3 

•"2.2 

. 

O      b£ 

*3  ^ 

2  ^ 

3^ 

S02 

o 

Ul 

U^i 

ow 

^ 

H 

Salt  made  by  solar  evaporation, 

7 

2 

991 

1000 

By  evaporation  with  artificial  heat, 

9 

0.5 

1 

988.5 

1000 

By  boiling  in  kettles,     .... 

11 

3 

6 

980 

1000 

In  the  specimens  of  salt  analyzed  by  Dr.  Henry,  the  proportion  of 
chloride  of  sodium,  in  1000  parts  of  the  salt  varied  from  937  to  988. 

USES.  The  uses  of  chloride  of  sodium  are  well  known.  Besides  its 
employment  in  seasoning  food,  and  in  preserving  meat  from  putrefac- 
tion, a  property  which  when  pure  it  possesses  in  a  high  degree,  it  is  used 
for  various  purposes  in  the  arts,  especially  in  the  formation  of  muri- 
atic acid  and  chloride  of  lime. 


226  SODIUM. 

TESTS.  Chloride  of  sodium  is  often  contaminated  with  sulphate  of 
lime,  and  the  muriates  of  lime  and  magnesia.  These  earths  may  be 
precipitated  as  carbonates,  by  boiling  a  solution  of  salt  for  a  few  min- 
utes with  a  slight  excess  of  carbonate  of  soda,  filtering  the  liquid  and 
neutralizing  with  muriatic  acid. 

REFERENCE.  Dr.  Henry'1  s  Analysis  of  various  kinds  of  British  and  for- 
eign Salt)  Repert.  of  Arts,  2dser.  xvii.  Dr.  J.  Van  Rensselapr^s  Essay  on 
Salt.  //.  C.  Beck's  account  of  the  Salt  and  Salt  Springs  of  Sahna,  N.  Y. 
Brard,  Mineralogie  Appliquee^  Aux.  Arts,  i.  248,  contains  an  account  of 
localities,  modes  of  manufacture,  fyc.  Holland's  Survey  of  Chesliire,  Eng. 
Art.  Cheshire,  in  the  Edinburgh  Encyclopedia.  Aikirfs  Dictionary,  Art. 
Muriate  of  Soda,  contains  a  concise  account  of  the  different  methods  of  manu- 
facturing salt. 

Iodide,  Sulphuret  and  Pkosphuret  of  Sodium. 

The  compounds  of  sodium  with  iodine,  sulphur  and  phosphorus,  are 
so  analogous  to  those  which  potassium  forms  with  the  same  elements, 
that  a  particular  description  of  them  is  unnecessary. 

On  nitrogen  gas  sodium  appears  to  have  no  action  ;  but,  when  heat- 
ed in  ammoniacal  gas,  hydrogen  is  disengaged,  and  a  nitruret  of  so- 
dium is  formed,  which  has  an  olive  green  colour,  is  fusible  at  a  low 
heat,  and  according  to  the  experiments  of  Gay  Lussac  and  Thenard, 
is  composed  of  100  parts  of  sodium,  and  19-821  nitrogen. — Thenard' 
ii.  431. 

SODIUM    AND    THE    METALS. 

The  history  of  these  compounds  is  very  similar  to  that  of  the  alloys 
of  potassium.  Like  those,  when  the  union  of  sodium  with  the  me- 
tals is  direct,  it  is  attended  with  the  evolution  of  caloric.  Some  of 
the  alloys  of  sodium  also  disengage  light  at  the  moment  of  their  com- 
bination, viz.  those  of  antimony,  tellurium  and  arsenic. — Thenard. 

SALTS    OP    SODA. 

Chlorate  of  Soda.— Atom.  Num.  108  75— Symb.  (5O+C1.) 
+(0+So.) 

PROPERTIES.  Soluble  in  three  parts  of  cold  water,  and  in  rather 
less  of  hot,  and  is  slightly  deliquescent ;  soluble  also  in  alcohol ;  crys- 
tallizes in  cubes  or  in  rhomboids  approaching  the  cube  in  form  ;  pro- 
duces a  sensation  of  cold  in  the  mouth,  and  a  taste  scarcely  to  be  dis- 
tinguished from  that  of  muriate  of  soda  ;  agrees  in  other  properties 
with  the  chlorate  of  potassa. 

PREPARATION.  This  salt  may  be  obtained  by  saturating  chloric  acid 
with  soda,  or  by  a  process  similar  to  that  for  preparing  chlorate  of  po- 
tassa ;  but  it  is  difficult  in  this  process  to  separate  it  from  muriate  of 
soda. — Ckevenix,  Phil.  Trans.  1802.  Vauqudin,  Ann.  dc  Chim.  xcv. 
96.  Ann.  of  Phil  vii.  39. 


SODIUM.  227 

Iodate,  of  Soda. — Atom.  Num.  197'3 — Symb.  (50+1) 


PROPERTIES.  Crystals  small  and  prismatic  :  decomposable  by  heat, 
and  is  converted  into  oxygen  and  iodide  of  sodium  ;  not  altered  by  ex- 
posure to  air  ;  detonates  feebly  with  sulphur  by  percussion. 

PREPARATION.  This  salt  is  formed  by  dissolving  iodine  in  solution 
of  soda  ;  a  white  compound  forms,  which  is  the  iodate  with  a  portion 
of  Hydriodate  of  Soda  ;  the  latter  may  be  removed  by  alcohol. 

Hydrofluntes  of  Soda.  —  Two  hydrofluates  of  soda  are  known  simi- 
lar in  constitution  to  those  of  potassa.  They  may  be  formed  by  simi- 
lar processes.  —  See  p.  217* 

Nitrate  of  Soda.  —  Atom.  Num.  S5-  3—  Symb.  (5O+N) 


SYN,     Cubic  Nitre,  of  the  older  chemists. 

PROPERTIES.  This  salt  crystallizes  in  rhombs,  soluble  in  three  parts 
of  water  at  60°  F  ,  and  in  less  than  its  weight  at  212°  ;  has  a  cool 
«harp  flavour,  and  is  somewhat  deliquescent. 

PREPARATION  AND  NATIVE  STATE.  This  salt  has  been  found  native 
in  Peru.  It  may  be  formed  by  saturating  carbonate  of  soda  with  ni- 
tric acid,  or  by  distilling  common  salt  with  three-fourths  of  its  weight 
of  nitric  acid.  When  the  former  process  is  adopted,  the  solution  must 
be  evaporated,  till  a  pellicle  appears  on  its  surface,  and  it  is  then  allow- 
ed to  cool. 

USES.  The  only  use  of  nitrate  of  soda  is  in  the  preparation  of  fire 
works.  A  powder  prepared  with  six  parts  of  this  salt,  one  of  sulphur 
and  one  of  carbon,  burns  with  a  fine  orange-yellow  flame,  but  with  much 
more  rapidity  than  a  like  powder  containing  nitre. 

Hyposulphite  of  Soda.  —  Deliquescent,  and  of  an  intensely  bitter  and 
nauseous  taste  ;  when  heated,  first  fuses,  then  dries  into  a  white  mass, 
and  at  length  takes  fire  and  burns  with  a  bright  yellow  flame  ;  insolu- 
ble in  alcohol,  and  has  the  property  of  rapidly  dissolving  the  chloride 
of  silver,  when  newly  precipitated. 

This  salt  may  be  prepared  in  the  same  way  as  the  analogous  salt  of 
potassa.  When  the  solution  is  evaporated  to  a  syrupy  consistency, 
it  crystallizes  in  silky  tufts,  radiating  from  a  centre,  and  rendering  the 
liquid  solid. 

Sulphite  of  Soda.  —  Crystallizes  in  white  transparent  four-sided  prisms, 
with  two  broad  sides  and  two  narrow  ones,  terminated  by  dihedral 
summits  ;  has  a  cool  sulphurous  taste  ;  is  soluble  in  four  parts  of  cold, 
or  less  than  its  weight  of  boiling,  water  ;  effloresces  upon  exposure  to 
the  air,  and  is  converted  into  a  sulphate. 

Sulphate   of  Soda.—  Atom.  Num.    161  -7—  Symb.  (3O+S) 
+(O+So)+10  aq. 

SYN.     Glauber's  Salts.     Sal  Mirabile. 
Discovered  by  Glauber,  whose  name  it  still  bears. 


228  SODIUM. 

PROPERTIES.  Taste  bitter,  cooling  and  saline  ;  crystallizes  in  four 
and  six-sided  prismatic  crystals,  but  its  primary  form  is  an  octahedron; 
effloresces  rapidly  when  exposed  to  the  air ;  undergoes  watery  fusion 
when  heated  ;  at  32°  F.  100  parts  of  water  dissolve  twelve  parts  of 
the  crystals,  48  parts  at  64-5,  100  parts  at  77°,  270  at  89  5°,  and  322 
at  91 -5°.  On  increasing  the  heat  beyond  this  point,  a  portion  of  the 
salt  is  deposited,  being  less  soluble  than  at  91 '5°. — Gay  Lussac. 

PREPARATION  AND  NATIVE  STATE.  This  salt  is  occasionally  met  with 
on  the  surface  of  the  earth,  and  is  frequently  contained  in  mineral 
springs.  It  may  be  made  by  the  direct  action  of  sulphuric  acid  on 
carbonate  of  soda ;  and  it  is  produced  in  large  quantity  as  a  residue  in 
the  processes  for  forming  muriatic  acid  and  chlorine. 

The  principal  use  of  sulphate  of  soda  is  in  pharmacy  ;  but  it  is 
sometimes  decomposed  for  the  purpose  of  obtaining  soda,  by  igniting 
it  with  chalk  and  charcoal,  or  with  iron  and  charcoal. — Sec  Mkin's  Dic- 
tionary, Art.  Muriate  of  Soda. 

Octohydrated  Sulpftate  of  Soda. — This  salt  occurs  in  the  form  of 
white,  four-sided  prisms,  and  contains,  according  to  Mr.  Faraday,  eight 
atoms  of  water  instead  often.  [Brande's  Jour.  xix.  152.]  It  is  form- 
ed by  crystallizing  in  a  supersaturated  solution  of  sulphate  of  soda, 
made  at  a  high  temperature  and  set  aside  for  some  days,  in  a  well  cork- 
ed phial.  I  obtained  a  portion  of  it  some  years  since,  in  a  bottle  of 
solution  of  sulphate  of  soda,  which  had  been  prepared  for  the  purpose 
of  exhibiting  the  effect  of  the  admission  of  air  in  determining  crystal- 
lization, and  upon  analysis  I  found  it  to  be  a  sulphate  of  soda,  but  in 
my  specimens,  the  proportions  of  water  did  not  exceed  seven  atoms. 

Anhydrous  Sulphate  of  Soda. — An  opaque  salt  whose  primary  form 
is  a  rhombic  octahedron,  and  specific  gravity  is  2'462.  It  is  formed  by 
evaporating  a  solution  of  common  sulphate  of  soda  saturated  at  91-5 
at  a  higher  temperature.  And  also  by  keeping  a  saturated  solution  of 
the  common  sulphate,  in  a  temperature  of  120°  in  a  stove. — Thomson  s 
Inorg.  Chem.  ii.  445.  Ann.  of  Phil,  xxviii.  403. 

Bisulphate  of  Soda.— Atom.  Num.  Ill-3—Symb.  2  (3O+S) 
+(0+So.) 

This  salt  may  be  formed  by  adding  sulphuric  acid  to  a  hot  solution 
of  sulphate  of  soda.  Large  rhomboidal  crystals  are  formed,  which 
are  soluble  in  twice  their  weight  of  water  at  60°  F.,  effloresce,  by  ex- 
posure to  air,  and  when  heated,  lose  their  excess  of  acid. — Crell's  An- 
nals, 1796. 

HypopJiosphite  and  Phosphite  of  Soda. — The  phosphite  of  soda  has 
not  been  examined.  Hypophosphite  of  soda  is  very  soluble  in  water 
and  alcohol.  Little  else  is  known  respecting  it. — Ann.  de  Cliim.  et  dc 
Phijs.  ii.  142. 

Phosphate  of  Soda.— Atom.  Num.  179-5—  Symb.  (2JO+P) 
+(0+So>fl2J  aq. 

SYK.     Sal  Perlatum. 

PROPERTIES.  Taste  saline  and  not  strong  ;  crystallizes  in  oblique 
prisms  which  effloresce  on  exposure  to  the  air7  and  require  four  parts  of 


SODIUM.  229 

cold,  and  two  of  boiling  water,  for  solution  ;  when  heated  it  fuses  and 
boils  up,  and  having  lost  its  water  of  crystallization,  runs  into  a  clear 
glass,  which  becomes  opaque  on  cooling. 

PREPARATION.  This  salt  is  usually  obtained  for  phamaceutical 
purposes,  by  saturating  the  impure  phosphoric  acid,  obtained  from  cal- 
cined bones  by  sulphuric  acid,  with  carbonate  of  soda  ;  the  liquor  is 
filtered,  evaporated  and  set  aside  tQ  crystallize.  —  Thomson's  First  Prin, 
ii.  270. 

Pyro-pliosphatc  of  Soda.—  This  name  has  been  given,  by  Mr.  Clark 
of  Glasgow,  to  phosphate  of  soda  which  has  been  subjected  to  a  red 
heat.  By  this  treatment,  not  only  its  water  is  expelled,  but  the  salt 
appears  to  undergo  some  change  of  constitution,  for  its  solution  gives 
with  nitrate  of  silver,  not  a  yellow  precipitate  like  that  of  the  com- 
mon phosphate,  but  a  white  one  ;  and  when  wholly  decomposed  by 
the  salt  of  silver,  the  remaining  solution  is  neutral,  not  acid,  as  when 
the  common  phosphate  has  been  decomposed.  Yet  no  gaseous  or 
other  product  can  be  collected,  except  water.  The  crystallized  phos- 
phate was  found  to  contain,  to  each  proportion,  25  proportions  of  wa- 
ter, [thus  differing  from  Dr.  Thomson]  of  which  24  were  separated  by 
a  sand  heat,  and  one  by  a  red  heat.  The  salt  had  then  acquired  the 
new  properties  which  have  been  just  described;  and  from  its  solution 
in  water,  crystals  were  obtained,  obviously  different  in  form  from 
those  of  common  phosphate  of  soda,  and  containing  only  10  proper 
tions  of  water. 

These  facts,  if  correctly  observed,  can  only  be  explained  by  suppos- 
ing a  new  arrangement  of  the  elements  of  the  phosphate,  occasioned  by 
the  high  temperature  to  which  it  has  been  exposed.  —  Henry'  Chem.  i. 
593.  Brewsters  Edin.  Jour.  vii.  299. 

Biphosphate  of  Soda.—  Atom.  Num.  134-2—  %w6.  2(2£O+  PJ 


PROPERTIES.  Taste  acid  and  saline  ;  reddens  vegetable  blues,  and 
is  usually  crystallized  in  four-sided  prisms,  terminated  by  four-sided 
pyramids. 

PREPARATION.  This  salt  is  prepared  by  adding  phosphoric  acid  to  a 
solution  of  the  neutral  phosphate  of  soda,  until  the  solution  ceases  to 
precipitate  muriate  of  baryta.  Being  very  soluble  in  water,  the  solu- 
tion must  be  concentrated,  in  order  that  it  may  crystallize  ;  and  it  re- 
quires a  long  time,  and  a  considerable  quantity  of  the  solution,  to  ob- 
tain large  crystals.  —  Thomson  s  First  Pi  in.  ii.  272. 

Phosphate  of  Soda  and  Ammonia.  —  Atom.  Num.  209*7?  — 
Symb.  (2£+  O+O+So)+(2jO+  N+HJ+10  aq. 

PROPERTIES.  Primary  form  a  right  rhombic  prism  ;  taste  saline  and 
cooling  ;  quite  soluble  in  water  :  when  heated,  pasts  with  its  water  of 
crystallization,  and  if  the  heat  is  raised  to  redness,  the  ammonia  is 
likewise  disengaged,  leaving  bi  phosphate  of  soda,  which  melts  into  a 
transparent  glass,  dissolves  in  water,  and  reddens  vegetable  blues. 

'  PREPARATION.     This  salt  exists  in  human  urine.     It  is  prepared  ar- 
tificially by  dissolving  one  proportion   of  muriate  of  ammonia  and  two 


230  SODIUM. 

of  phosphate  of  soda  in  a  small  quantity  of  boiling  water.  As  the  li- 
quid cools,  prismatic  crystals  of  the  double  phosphate  are  deposited, 
while  muriate  of  soda  remains  in  solution. 

This  salt  has  long  been  known  under  the  names  of  fusible  and  micro- 
cosmic  snlt.  It  is  sometimes  employed  by  mineralogists  as  a  flux  in 
experiments  made  by  the  blow-pipe. — Fourcroy,  Ann.  de  Chim.  vii.  183. 

Phosphate  of  Soda  and  Potassa. — This  salt  is  obtained,  according  to 
Mitscherlich,  by  adding  carbonate  of  soda  to  a  solution  of  biphosphate 
of  potassa,  until  effervescence  ceases.  Upon  evaporation  the  double 
salt  crystallizes. — Berzelius,  iii.  463. 

Carbonate  of  Soda.— Atom.  Num.  143-3 — Symb.  (2O+C) 
+(O+So)+lO  aq. 

SYN.     Subcarbonate  of  Soda  of  the  Pharmacopeia. 

PROPERTIES.  Crystallizes  in  octahedrons,  with  a  rhombic  base,  the 
acute  angles  of  which  are  generally  truncated  ;  the  crystals  effloresce 
on  exposure  to  the  air,  and.  when  heated,  dissolve  in  their  water  of 
crystallization  ;  by  continued  heat  are  rendered  anhydrous  without 
loss  of  carbonic  acid;  dissolve  in  about  two  parts  of  cold,  and  less 
than  their  weight  of  boiling  water,  and  the  solution  has  a  strong  alka- 
line taste  and  reaction. 

PREPARATION.  The  carbonate  of  soda  of  commerce  is  obtained  by 
lixiviating  the  ashes  of  sea-weeds.  The  best  variety  is  known  by  the 
name  ofbarilia,  and  is  derived  chiefly  from  the  salsola  soda  and  salicor- 
niaherbacea.  A  very  inferior  kind  known  by  the  name  of  kelp,  is  pre- 
pared from  sea- weeds  on  the  northern  shores  of  Scotland.  The  purest 
barilla,  however,  though  well  fitted  for  making  soap  and  glass,  and  for 
other  purposes  in  the  arts,  always  contains  the  sulphates  and  muri- 
ates of  potassa  and  soda,  and  on  this  account  is  of  little  service  to  the 
chemist.  A  purer  carbonate  is  prepared  by  heating  a  mixture  of  sul- 
phate of  soda,  saw-dust  and  lime,  in  a  reverbatory  furnace.  By  the 
action  of  the  carbonaceous  matter,  the  sulphuric  acid  is  decomposed — 
its  sulphur  partly  uniting  with  lime  and  partly  being  dissipated  in  the 
form  of  sulphurous  acid,  while  the  carbonic  acid,  which  is  generated 
during  the  process,  unites  with  soda.  The  carbonate  of  soda  is  then 
obtained  by  lixiviation  and  crystallization.  It  is,  however,  difficult  to 
obtain  this  salt  quite  free  from  sulphuric  acid.— [For  other  processes, 
see  Berzelius,  Traite  de  Chim.  iii.  466.] 

The  quantity  of  real  carbonate  in  the  soda  of  commerce  may  be  con- 
veniently estimated  by  its  neutralizing  power,  which  may  be  ascer- 
tained in  the  mode  described  in  the  remarks  upon  potash,  [p.  222.] 

REFERENCES.  Report  on  the  different  methods  of  extracting  Soda  from 
Sea  Salt)  by  Lelievre^  Pelletier.  tifc.  Jour  de  Phys.  or  Repeit.  of  Arts,  2U 
ser.  x.  230.  Gay  Lussac  and  Wetter  on  the  Assay  of  Samples  of  Soda  and 
Barilla  of  commerce ,  Ibid,  xxxvii.  241.  On  obtaining  Soda  from  Kelp, 
Muriate  and  Sulphate  of  Soda,  ChaptaPs  Chem.  ii.  107.  Paikes1  Chern. 
Essay st  iii.  121. 


SODIUM.  231 

Sesquicarbonate  of  Soda.  —  Atom.   Num.  82*3  —  Symb.  1J 

aq. 


This  salt  is  found  native  in  Barbary,  where  it  is  known  by  the  name 
of  Trona.  It  constitutes  hard  masses,  which  do  not  deliquesce  in  the 
air  ;  and  it  is  said  to  be  employed  in  the  north  of  Africa,  where  rain  sel- 
dom falls,  for  building  the  walls  of  houses.  It  is  manufactured  in  Lon- 
don for  the  use  of  the  soda-water  makers,  and  is  sold  in  the  state  of  a 
white  powder.  It  does  not  appear  to  be  susceptible  of  crystallization. 
Thomson's  First  Prin.  ii.  267.  R.  Phillips,  in  Brandes  Jour.  vii.  294. 

Bictirbonate  of  Soda.—  Atom.  Num.  8±'3—Symb.  2  (2O+C) 
+(0+So.)  +  l  aq. 

PROPERTIES.  Taste  milder  than  that  of  the  carbonate;  requires  9 
or  10  times  its  weight  of  water  at  603  F.  for  solution,  which  when  heat- 
ed liberates  a  part  of  the  carbonic  acid  ;  affects  colour  tests  in  the 
same  manner  as  the  subcarbonate  ;  by  exposure  to  a  low  red  heat  it  is 
rendered  anhydrous. 

PREPARATION.  This  salt  may  be  prepared  by  saturating  a  weak  so- 
lution of  carbonate  of  soda,  bypassing  through  it  a  stream  of  car- 
bonic acid  ;  or  by  dissolving  14  parts  of  carbonate  of  ammonia  in  a 
solution  of  100  parts  of  carbonate  of  soda  and  evaporating  at  a  gentle 
heat.  —  Thomson's  First  Prin.  ii.  267. 

Compound   Carbonate  and  Chloride  of  Soda.  —  Disinfecting 
Soda  Liquid  of  Labarraque. 

The  nature  of  this  compound,  sometimes  called  also  the  Chloride  of 
Soda,  does  not  appear  to  have  been  definitively  settled.  It  has  been 
investigated  by  Dr.  Granville,  Mr.  Phillips  and  Mr.  Faraday.  —[See 
Branded  Jour.  JV.  £  i.  371.  and  ii.  84.  Phil.  Mag.  and  Ann.  i".  376.] 

It  is  most  probable  that  this  substance  consists  merely  of  chlorine 
held  in  solution  by  the  dissolved  salt  —  and  that  it  is  not  a  definite 
compound  of  chlorine  and  soda,  or  of  chlorine  and  the  carbonate  of 
soda.  —  SUl.  Jour.  xiv.  251. 

PROPERTIES.  This  compound,  prepared  according  to  the  direc- 
tions of  Labarraque,  has  a  pale  yellow  colour  and  a  slight  odour  of 
chlorine  ;  taste  at  first  sharp,  saline  and  scarcely  at  all  alkaline,  but 
it  produces  a  persisting  biting  effect  on  the  tongue  ;  it  first  reddens, 
then  destroys  the  colour  of  turmeric  paper  ;  when  boiled  it  does  not 
give  out  chlorine,  nor  is  its  bleaching  powers  perceptibly  impaired  ; 
and  if  carefully  evaporated,  it  yields  a  mass  of  damp  crystals,  which, 
when  redissolved,  bleach  almost  as  powerfully  as  the  original  liquid  ; 
when  rapidly  evaporated  to  dryness,  the  residue  contains  scarcely 
any  chlorate  of  soda  or  chloride  of  sodium,  but  it  has  nevertheless 
lost  more  than  half  its  bleaching  power,  and  therefore  chlorine  must 
have  been  evolved  during  the  evaporation.  The  solution  deteriorates 
gradually  by  keeping,  chloric  acid  and  chloride  of  sodium  being  gene- 
rated. When  allowed  to  evaporate  spontaneously,  chlorine  gas  is 
gradually  evolved,  and  crystals  of  carbonate  of  soda  remain.  —  Tur- 
ner. 


232  SODIUM. 

PREPARATION.  This  compound  is  easily  prepared  by  transmitting 
a  current  of  chlorine  gas  into  a  cold  and  rather  dilute  solution  of 
caustic  soda,  or  of  the  carbonate  of  that  alkali.  It  may  also  be  form- 
ed easily  and  cheaply,  and  of  uniform  strength,  by  decomposing  chlo- 
ride of  lime  with  carbonate  of  soda,  as  proposed  by  M.  Pa  yen. — 
[Brande's  Jour.  N.  8.  i.  236.]  The  formula  of  Labarraque  is  as  fol- 
lows :  2800  grains  of  crystallized  carbonate  of  soda  are  dissolved  in 
1*28  pints  of  water,  and  through  the  solution,  contained  in  a  Woulfe's 
apparatus,  is  transmitted  the  chlorine,  evolved  from  a  mixture  of  967 
grains  of  sea  salt  and  750  grains  of  peroxide  of  manganese,  when  ac- 
ted on  by  967  grains  of  sulphuric  acid,  diluted  with  750  grains  of  wa- 
ter, the  gas  being  passed  through  pure  water  to  remove  any  accom- 
panying muriatic  acid. 

USES.  This  compound  may  be  employed  for  bleaching,  and  for  all 
purposes  to  which  chlorine  gas  or  its  solution  was  formerly  applied. 
It  is  now  much  used  in  removing  the  offensive  odour  arising  from 
drains,  sewers,  or  all  kinds  of  animal  matter  in  a  state  of  putrefaction. 
Bodies  disinterred  for  the  purpose  of  judicial  inquiry,  or  parts  of  the 
body  advanced  in  putrefaction,  may,  by  its  means,  be  rendered  fit  for 
examination  ;  and  it  is  employed  in  surgical  practice  for  destroying 
the  fetor  of  malignant  ulcers.  Clothes  worn  by  persons  during  pesti- 
lential diseases  are  disinfected  by  being  washed  with  this  compound. 
It  is  also  used  in  fumigating  the  chambers  of  the  sick  ;  for  the  disen- 
gagement of  chlorine  is  so  gradual,  that  it  does  not  prove  injurious  or 
annoying  to  the  patient.  In  all  these  instances,  chlorine  appears  ac- 
tually to  decompose  noxious  exhalations  by  uniting  with  the  elements 
of  which  they  consist,  and  especially  with  hydrogen. 

REFERENCES.  An  Essay  on  the  use  of  the  Chlorurets  of  Oxide  of  Sodi- 
um and  Lime  as  powerful  disinfecting  agents,  fyc.  by  Thomas  Alcock.  The 
Memoir  of  Labarraque  ^  translated  by  Dr.  Jacob  Porter.  See  also  facts  stated 
by  the  author  in  a  paper  on  these  compounds,  in  the  Neic-  York  Med.  and 
Phys.  Jour.  vii.  62. 

Biborate  of  Soda.— Atom.  Num.  151-3— %»i&.  2(2O+B)+ 

(0+So)+8  aq. 

SYN.     Subborate  of  Soda.     Borax. 

PROPERTIES.  Crystallizes  in  prisms  with  irregular  sides  ;  efflores- 
ces in  the  air  ;  fuses  when  ignited,  and  then  loses  its  water  of  crystal- 
lization, and  is  changed  into  a  white  powder,  which,  on  increasing  the 
heat,  leaves  a  transparent  mass,  called  Glass  of  Borax,  a  substance  of 
great  use  in  experiments  with  the  blow-pipe  ;  it  changes  the  colour 
of  svrup  of  violets  to  green,  and  was,  therefore,  considered  as  a  sub- 
salt. 

PREPARATION  AN{>  NATIVE  STATE.  This  salt  occurs  native  in  gome 
of  the  lakes  of  Thibet  and  Persia,  and  is  extracted  from  this  source  by 
evaporation.  It  is  imported  from  India,  in  a  crude  state,  under  the 
name  of  Tincal,  which  after  being  purified,  constitutes  the  refined  bo- 
rax of  commerce. — Thenard,  iii.  87. 

A  new  variety  of  borax  is  obtained  by  dissolving,  in  boiling  water, 
as  much  common  borax  as  will  give  a  solution  of  specific  gravity  1-246. 
It  forms  octahedral  crystals  and  contains  only  half  the  water  of  com- 
mon borax. — M.  Pay  en,  Brande's  Jour.  N.  S.  iii.  483. 


LITHIUM.  233 

REFERENCES.  Thomson's  I  irst  Prin.  ii.  270.  MM.  Robiquet  and  Mar* 
(•hand's  process  for  refining  Borax.  Ann.  de  Chim.  et  de  Phys.  viii.  359. 
Ann.  of  Phil.  xiii.  61.  Berzelpesrw.  469. 

Selenites  and  Selenate  of  Soda. — Berzelius  describes  three  distinct  se- 
lenites  of  soda,  differing  in  the  amount  of  acid  which  they  contain. 
A  Selenate  of  Soda  is  also  recognized.  —  Traite  de  Chim.  iii.  481. 

TESTS  OF  THK  SALTS  OF  SODA.  1.  Upon  adding  sulphuric  acid  to 
soda  a  salt  is  obtained,  which,  by  its  taste  and  form,  is  easily  recogniz- 
ed as  Glauber's  salt,  or  sulphate  of  soda.  2.  All  its  salts  are  soluble 
in  water,  and  are  not  precipitated  by  any  re-agent.  3.  On  exposing 
its  salts,  by  means  of  platinum  wire,  to  the  blow-pipe  flame,  they  com- 
municate to  it  a  rich  yellow  colour.  According  to  M.  Harkort,  of 
Freyberg,  potash  with  nickel  gives  a  blue  glass  before  the  blow-pipe, 
while  soda  gives  a  brown  glass.  This  is  said  to  be  a  very  delicate 
test,  provided  the  nickel  is  perfectly  free  from  cobalt. — Ure's  Ckem. 
Diet. 


SECTION  III. 

LITHIUM. 
Atom.  Num.  10 — Symb.  L. 

Lithium  is  a  white  coloured  metal  like  sodium,  which  was  first  ob- 
tained fiorn  lithia  by  Sir  H.  Davy,  by  means  of  galvanism  ;  but  it  was 
oxidized  and  reconverted  into  the  alkali  with  such  rapidity  that  it  could 
not  be  collected. 

LITHIUM    A?s7D    OXYGEN. 

Oxide  of  Lithium  or  Lithia. — Atom.  Num.  18 — Symb.  O+L. 

Discovered  in  1818,.  by  Arfwedson  of  Sweden,  in  the  mineral  call- 
ed Pctalite,  and  since  that  time  also  found  in  spodumene,  lepidolite, 
and  in  several  varieties  of  mica. 

PROPERTIES.  Soluble  in  water,  and  like  the  other  alkalies  has.  an 
acrid,  caustic  taste  ;  changes  vegetable  blues  to  green  ;  when  heated 
in  contact  with  platinum,  it  fuses  and  then  acts  on  the  metal  ;  is  dis- 
tinguished from  potassa  and  soda  by  its  greater  neutralizing  power  ; 
when  exposed  to  the  air  it  absorbs  carbonic  acid  and  becomes  opaque. 

PREPARATION.  A  good  process  for  preparing  lithia  is  to  mix  pow- 
dered spodumene  with  twice  its  weight  of  pulverized  fluor-spar,  and 
with  sulphuric  acid  ;  then  to  heat  the  mixture  until  the  hydrofluoric 
acid  with  the  silica  is  volatilized,  and  afterwards  to  separate  the  sul- 
phate of  lithia  by  solution.  This  salt  may  be  decomposed  by  the  ace- 
tate of  baryta,  and  the  acetate  of  lithia,  thus  obtained,  is  converted  into 
a  carbonate  by  exposure  to  a  red  heat — By  the  action  of  lime  the  car- 
bonate may  then  be  brought  to  the  state  of  caustic  hydrate.  Berzelius 
describes  other  processes  for  obtaining  this  alkali. — See  Traite  de  Chim. 
ii.  37. 


234  LITHIUM. 

REFERENCES.  Arfwedson,  Ann.  de  Chim.  ft  de  Phys.  x.  82.  Berzelius 
on  Lithia  in  Pttalite,  S?c.  Ann.  of  Phil.  xi.  291,  373,  447.  Gmeliifs  exam- 
ination of  the  chemical  properties  of  Lithia^  Ann.  of  Phil.  xv.  341,  374. 

LITHIUM    AND    CHLORINE. 

Chloride  of  Lithium. — Atom.  Num.  45.45 — Symb.  Cl+L. 

This  compound  may  be  obtained  by  evaporating  the  muriate  of  lithia 
to  dryness  and  fusing  the  residne.  It  is  white  and  semi-transparent, 
extremely  deliquescent,  soluble  in  alcohol,  is  decomposed  when  strong- 
ly heated  in  the  open  air,  when  it  parts  with  chlorine,  absorbs  oxygen 
and  becomes  highly  alkaline  ;  it  is  very  difficultly  crystallizable  and 
tinges  the  flame  of  alcohol  red.  In  all  these  respects  it  differs  from 
the  similar  compounds  of  potassa  and  soda. 

SALTS    OF    LITHIA. 

These  have  not  been  very  minutely  examined,  as  the  basis  has  not 
yet  been  very  abundantly  obtained. 

Nitrate  of  Lithia  is  very  soluble,  and  by  evaporation  crystallizes 
sometimes  in  regular  rhomboids,  sometimes  in  needles.  It  is  extreme- 
ly fusible  ;  and  at  the  instant  when  it  has  cooled,  it  attracts  moisture 
from  the  air  and  becomes  fluid. 

Sulphate  of  Lithia  crystallizes  in  small  prisms,  of  a  shining  white 
colour.  It  is  more  fusible  and  soluble  than  sulphate  of  potassa,  and 
has  a  saline  and  not  a  bitter  taste. 

Bisulphate  of  Lithia  is  produced  by  adding  an  excess  of  sulphuric  acid 
to  the  sulphate.  It  is  more  fusible  and  less  soluble  in  water  than  the 
sulphate. 

Phosphate  of  Lithia  is  formed  by  adding  phosphate  of  ammonia  with 
excess  of  base  to  sulphate  of  Lithia,  when  an  insoluble  phosphate  falls 
down.  By  this  property  it  may  be  separated  from  potassa  and  soda. 
There  exists  also  a  biphosphatc. 

REFERENCES.  On  the  Salts  of  Lithia ,  see  Gmeliji1^ paper  in  the  Ann.  of 
Phil,  xv.,  and  Berzelius,  Traitede  Chim.  iii.  488. 

TESTS  OF  THE  SALTS  OF  LITHIA,  Lithia  may  be  distinguished  from 
potassa  and  soda  by  forming  sparingly  soluble  salts  with  carbonic  and 
phosphoric  acids  ;  by  affording  deliquescent  salts  with  muriatic  and 
nitric  acids,  which  are  freely  soluble  in  alcohol.  This  alchoholic  solu- 
tion burns  with  a  red  flame  ;  and  all  the  salts  of  lithia,  when  heated 
on  platinum  wire  before  the  blow-pipe,  tinge  the  flame  of  a  red  colour, 
— Berzelius  on  the  Blow- Pipe.  Rose's  Manual  of  Analytical  Chemis- 
try, 54. 


BARIUM.  235 


CLASS  II. 

METALS,    WHICH    WHEN    COMBINED  WITH    OXYGEN,  FORM    ALKA- 
LINE   EARTHS. 


SECTION  IV. 

BARIUM. 
Atom.  Num.  GS'7— Symb.  Ba. 

The  metallic  basis  of  baryta  was  discovered  by  Sir  H.  Davy  in  1808  ; 
but  it  has  hitherto  been  obtained  only  in  small  quantities. 

PROPERTIES.  Colour  dark  grey,  with  a  lustre  inferior  to  that  of  cast 
iron  ;  specific  gravity  greater  than  water ;  it  attracts  oxygen  with 
avidity  from  the  air,  and  is  converted  into  baryta  ;  effervesces  strong- 
ly, from  the  escape  of  hydrogen  when  thrown  into  water,  a  solution  of 
baryta  being  produced. 

PREPARATION.  This  metal  was  obtained  by  Sir  H.  Davy,  by  a  pro- 
cess suggested  by  Berzelius  and  Pontin.  It  consists  in  forming  car- 
bonate of  baryta  into  a  paste  with  water,  and  placing  a  globule  of 
mercury  into  a  little  hollow  made  in  its  surface.  The  paste  was  laid 
upon  a  platinum  tray  which  communicated  with  the  positive  pole  of  a 
galvanic  battery  of  100  double  plates,  while  the  negative  wire  was 
brought  into  contact  with  the  mercury.  The  baryta  was  decomposed, 
and  its  barium  entered  into  combination  with  mercury.  This  amal- 
gam was  then  heated  in  a  vessel  free  from  air,  by  which  means  the 
mercury  was  expelled,  and  barium  obtained  in  a  pure  form. — Tamer, 
See  also,  Berzelius,  Traite  de  Chim,  ii.  346,  for  a  notice  of  another  pro- 
cess. 

BARIUM    AND    OXYGEN. 

Two  compounds  of  barium  and  oxygen  are  at  present  known. 
Protoxide  of  Barium. — Atom.  Num.  76-7 — Symb.  O+Ba. 

Discovered  by  Scheele  in  1774,  and  called  Barytes  or  Baryta,  from 
the  great  density  of  its  compounds. 

PROPERTIES.  A  gray  powder,  the  specific  gravity  of  which  is  about 
4  ;  it  requires  a  high  temperature  for  fusion  ;  taste  sharp  and  alkaline  ; 
converts  vegetable  blue  colours  to  green,  and  neutralizes  the  strongest 
acids  ;  has  a  strong  affinity  for  water,  and  when  mixed  with  that  liquid 
it  slakes  in  the  same  manner  as  quick  lime,  but  with  the  evolution  of 
a  more  intense  heat,  which,  according  to  Dobereiner,  sometimes 


236  BARIUM. 

amounts  to  luminousness  —  the  result  being  a  white  bulky  hydrate, 
fusible  at  a  red  heat,  and  which  bears  the  highest  temperature  of  a 
smith's  forge  without  parting  with  its  water  ;  evolves  light  when  act- 
ed on  by  concentrated  sulphuric  acid. 

REFERENCES.     Ann.  of  Phil,  xviii.  77.  Ann.  de  Chim.  et  de  Phys.  xxxvii. 
223,  or  Repert.  of  Pat.  Invent,  vii.  94. 

Hydrate   of  Baryta.—  Atom.  Ntmi.  857—  Symb.    (O+Ba) 


This  hydrate  is  soluble  in  twice  its  weight  of  boiling  water,  and  in 
twenty  parts  of  water  at  the  temperature  of  6(P  F.  A  saturated  so- 
lution of  baryta  in  boiling  water  deposites,  in  cooling,  transparent 
flattened  prismatic  crystals,  which  are  composed,  according  to  Mr. 
Dalton,  of  one  proportion  of  baryta  and  20  proportions  of  water. 

The  Aqueous  solution  of  Baryta  is  an  excellent  test  of  the  presence 
of  carbonic  acid  in  the  atmosphere,  or  in  other  gaseous  mixtures.  The 
carbonic  acid  unites  with  the  baryta,  and  a  white  insoluble  precipitate, 
carbonate  of  baryta,  subsides.  ,,,, 

PREPARATION.  Baryta  may  be  prepared  as  above  suggested,  by  ex- 
posing barium  to  air.  It  may  also  be  obtained  by  decomposing  ni- 
trate of  barjta  at  a  red  heat  ;  or,  as  was  ascertained  by  Dr.  Hope,  by 
exposing  carbonate  of  baryta,  contained  in  a  black  lead  crucible,  to 
an  intense  white  heat  ;  a  process  which  succeeds  much  better,  when 
the  carbonate  is  intimately  mixed  with  charcoal. 

Peroxide  of  Barium.  —  Atom.  Num.  84-7—  Symb.  2O+Ba. 

A  grayish  white  substance,  employed  by  Thenard  in  the  preparation 
of  peroxide  of  hydrogen,  (p.  116.)  It  may  be  formed  by  conducting 
dry  oxygen  gas  over  pure  baryta  at  a  low  red  heat.  An  easier  pro- 
cess, recommended  by  M.  Quesneville,  junr.,  is  to  introduce  nitrate  of 
baryta  into  a  luted  retort  of  porcelain,  to  which  is  attached  a  Welter's 
safety  tube,  terminating  under  an  inverted  jar  full  of  water.  Heat  is 
gradually  applied  to  the  retort,  and  a  red  heat  continued  as  long  as 
there  is  any  disengagement  of  nitric  oxide  or  nitrogen  gas.  When 
these  have  ceased  and  pure  oxygen  passes  over,  which  is  a  proof  of  all 
the  nitrate  being  decomposed,  the  process  is  discontinued.  The  per- 
oxide of  barium  is  then  found  in  the  retort. 

REFERENCES.  Ann.  de  Chim.  el  de  Pliys.  xxxv.  108.  Thenard,  Tralte  de 
Chim.  ii.  328.  Edin.  Jour,  of  Science,  ii.  180.  Webster's  Brande. 

BARIUM    AND    CHLORINE. 

Chloride  of  Barium.—  Atom.   Nam.  104-15—  Symb.  Cl+Ba. 

PROPERTIES.  Taste  pungent  and  acrid  ;  requires  five  times  its 
weight  of  water  at  60°  for  solution  ;  unaltered  by  exposure  to  the  air  ; 
decomposed  by  sulphuric  acid  and  the  alkaline  carbonates  ;  when  dis- 
solv^d  in  water,  is  supposed  to  be  changed  into  Muriate  of  Baryta, 
which  may  be  obtained  from  the  solution  by  evaporation  in  the  form  of 
tables  or  eight  sided  pyramids,  applied  base  to  base.  These  crystals, 


BARIUM.  237 

according  to  Dr.  Thomson,  consist  of  one  proportion  of  muriate  of 
baryta  and  rone  of  water. 

PREPARATION.  The  chloride  is  generated  when  chlorine  gas  is  con- 
ducted over  baryta  at  a  red  heat,  and  oxygen  gas  is  disengaged.  It 
may  also  be  formed  by  heating  to  redness  the  crystallized  muriate  of 
baryta.  This  salt  is  best  prepared  by  dissolving  either  the  artificial  or 
native  carbonate,  or  the  sulphuret,  in  dilute  muriatic  acid  ;  and  after- 
wards evaporating  and  crystallizing.  In  this  form  it  is  employed  as  a 
test  for  the  presence  of  sulphuric  acid. 

REFERENCES.  The  prof-esses  for  the  preparation  of  Muriate  of  Baryta  by 
La  Grange,  fyc.  Ann.  de  Chitn.,  orRepert.  of  Arts,%dser.  iv.  439.  viii.  139. 
Medical  and  Chemical  History  of  ,  New-England  Med.  Jour.  iii.  23.  On  the 
poisonous  properties  of  f Iiis  and  other  compounds  of  Baryta^  see  Christison  on 
Poisons ,  431. 

BARIUM    AND    BROMINE. 

Bromide  of  Barium. 

This  has  been  obtained  by  boiling  proto-bromide  of  iron  with  moist 
eaibonate  of  baryta  in  excess,  evaporating  the  filtered  solution,  and 
heating  the  residue  to  redness.  The  product  crystallizes  by  careful 
evaporation  in  white  rhombic  prisms,  which  have  a  bitter  taste,  are 
slightly  deliquescent,  and  are  soluble  in  water  and  alcohol. 

BARIUM    AND    IODINE. 

Iodide  of  Barium. 

This  compound  may  be  formed  by  acting  upon  baryta  by  hydri- 
odic  acid  and  evaporating  the  solution.  It  m&y  also  be  formed  by  heat- 
ing baryta  in  hydriodic  gas ;  water  and  iodide  of  barium  are  the  re- 
sults. When  thrown  into  water,  it  is  converted  into  Hydriodate,  of 
Baryta. 

BARIUM    AND    SULPHUR. 

Sulphuret  of  Barium. 

The  protosulphuret  of  barium  may  be  prepared  from  sulphate  of 
baryta  by  the  action  of  charcoal  or  hydrogen  gas  at  a  high  tempera- 
ture. It  dissolves  readily  in  hot  water,  forming  the  hydrosulphuret  of 
baryta.  By  means  of  this  solution,  all  the  chief  salts  of  baryta  may 
be  procured.  Thus,  by  adding  an  alkaline  carbonate,  carbonate  of 
baryta  is  precipitated  ;  and  when  muriatic  acid  is  added,  sulphuretted 
hydrogen  is  evolved,  and  muriate  of  baryta  produced.  A  solution  of 
pure  baryta  may  also  be  obtained  from  the  hydrosulphuret,  by  boiling 
it  with  peroxide  of  copper,  until  the  filtered  solution  no  longer  gives 
a  dark  precipitate  with  acetate  of  lead.  The  crystallized  hydrate  of 
baryta  is  easily  procured  by  means  of  this  solution. — Turner. 


23S  BARIUM. 

BARIUM    AND    PHOSPHORUS, 

Phosphuret  of  Barium. 

This  compound  decomposes  water  and  gives  out  phosphuretted  hy- 
drogen like  the  preceding  phosphurets.  It  may  be  formed  by  heating: 
to  redness  anhydrous  caustic  baryta  in  a  glass  matrass,  furnished  with 
a  long  neck,  and  then  throwing  pieces  of  phosphorus  into  it, — Berze- 
lius,  ii.  358* 

SALTS    OP    BARYTA. 

Chlorate  of  Baryta.— Atom.  Num.  152-15—  Symb.  (50+CP, 
+  (0+Ba.) 

PROPERTIES.  Crystallizes  in  the  form  of  four-sided  prisms  ;  taste 
pungent  and  austere  ;  requires  for  solution  about  four  times  its  weight 
of  \\ater  at  50°  F.y  and  its  solution  when  pure  is  not  precipitated  ei- 
ther by  nitrate  of  silver  or  muriatic  acid  ;  by  a  red  heat  loses  39  per 
cent.,  and  the  remainder  is  alkaline. 

PREPARATION.  The  readiest  mode  of  preparing  this  salt  is  by  the 
process  of  Mr.  Wheeler.  On  digesting,  for  a  few  minutes,  a  concen- 
trated solution  of  chlorate  of  potassa  with  a  slight  excess  of  silicated 
hydrofluoric  acid,  the  alkali  is  precipitated  in  the  form  of  an  insoluble 
double  hydroftuate  of  silica  and  potassa,  while  chloric  acid  remains  in 
solution.  The  liquid,  after  filtration,  is  neutralized  by  carbonate  of 
baryta,  which  likewise  throws  down  the  excess  of  hydrofluoric  acid 
and  silica.  The  silicated  hydrofluoric  acid  employed  in  the  process,  is 
made  by  conducting  fluosiiicic  acid  gas  into  water. 

This  salt  is  of  interest,  as  being  the  compound  employed  in  the  for- 
mation of  chloric  acid. 

lodate  of  Baryta.— Atom.  Num.  2427—  Symb.  (5O+I) 
+  (0+Ba.) 

An  extremely  insoluble  salt,  formed  by  adding  iodine  to  solution  of 
baryta,  from  which  the  iodate  precipitates  in  the  state  of  a  white  pow- 
der, and  may  be  edulcorated  by  washing   with  distilled  water.     When 
strongly  heated,  oxygen  and  iodine  are  evolved  from  it,  and  baryta  re 
mains. 

Nitrate  of  Baryta. — Atom.   Num.  130-7 — Symb.   (5O+N) 
•f(O+Ba.) 

PROPERTIES.  Crystallizes  in  transparent  octahedrons  ;  not  altered 
by  exposure  to  air  ;  soluble  in  12  times  its  weight  of  water,  at  60°  F. 
and  3  or  4  parts  of  boiling  water ;  insoluble  in  alcohol  ;  in  a  red  heat 
its  acid  is  decomposed,  and  the  earth  remains  pure. 

This  salt  is  easily  prepared  by  dissolving  the  natural  or  artificial 
carbonate  of  baryta  in  nitric  acid,  diluted  with  eight  or  ten  times  its 
weight  of  water,  or  by  decomposing  the  sulphuret  of  barium  by  nitric 
acid  and  evaporating  the  solution.  It  is  employed  as  a  test,  and  when 
mixed  with  equal  parts  of  charcoal  is  used  for  making  green  fire. 


BARIUM,  239 

Hyposulphite  of  Baryta.— A  white  shining  scaly  powder,  slightly 
soluble  in  water,  and  obtained  by  adding  muriate  of  baryta  to  a  con- 
centrated solution  of  hyposulphite  of  lime. 

Sulphite  of  Baryta. — An  insoluble  compound,  formed  by  mixing 
sulphite  of  potassa  and  muriate  of  baryta. 

Sulphate   of  Baryta.— Atom.  Num.  116-7—  Symb.  (3O+S) 
+(0+Ba.) 

PROPERTIES.  This  salt,  sometimes  called  Heavy  Spar,  is  white,  in- 
sipid, absolutely  insoluble  in  water,  sulphuric  acid  forming  a  sudden 
and  sensible  precipitation  in  water,  which  contains  1-20,000  of  bary- 
ta, or  even  of  any  barytic  salt :  it  dissolves  sensibly  in  concentrated 
sulphuric  acid,  but  does  not  dissolve  in  the  weak  acid  ;  at  a  very  elevated 
temperature  it  is  fused. — [Thenard.']  When  heated  to  redness  it  ac- 
quires the  property  of  phosphorescence  and  is  sometimes  called  Bolog- 
na Phosphorus. — [For  details  of  the  process,  see  Henry's  Chem.  i.  630.] 
It  is  decomposed  by  being  subjected  to  high  heat  in  contact  with  char- 
coal. 

NATIVE  STATE  AND  PREPARATION.  Sulphate  of  baryta  or  heavy  spar, 
is  found  abundantly  in  nature.  It  is  met  with  in  the  mines  of  Cum- 
berland and  Westmoreland,  and  in  Transylvania,  Hungary.  Saxony, 
and  Hanover.  It  also  occurs  in  various  parts  of  the  United  States,  es- 
pecially in  company  with  galena,  in  Missouri  and  Illinois. 

This  salt  may  be  obtained  artificially  by  turning  a  solution  of  sul- 
phate of  potassa  or  of  soda  into  a  solution  of  the  nitrate  or  muriate  of 
baryta.  In  this  state  it  is  used  as  a  pigment  under  the  name  of 
Permanent  White. 

As  the  sulphate  of  baryta  is  a  common  and  abundant  native  product, 
it  is  made  use  of  for  obtaining  pure  baryta  and  the  other  salts.  For 
this  purpose  several  processes  have  been  contrived.  The  most  con- 
venient one  consists  in  mixing  the  sulphate,  finely  powdered,  in  the 
proportion  of  six  parts,  with  one  part  of  powdered  charcoal,  and  ex- 
posing these  to  a  red  heat,  for  half  an  hour,  in  an  earthen  crucible. 
This  converts  the  sulphate  into  sulphuret  of  barium,  which  is  to  be 
dissolved  in  hot  water,  and  the  solution  filtered.  To  this  solution  we 
may  add  dilute  nitric  acid,  if  we  wish  to  obtain  nitrate  of  baryta,  or 
muriatic  acid,  if  the  muriate  is  required.  The  solution  is  then  to  be 
evaporated  and  crystallized. 

REFERENCE.     Parkes*1  Chem.  Essays,  ii.  186. 

Hypophosphite  of  Baryta. — A  very  soluble  salt,  crytallizable  with  dif- 
ficulty.— Dulong,  Ann.  de  Chim.  et  de  Phys.  ii.  142. 

Phosphite  of  Baryta.  —  Obtained  by  Berzelius,  by  adding  muriate  of 
baryta  to  phosphite  of  ammonia  ;  a  crust  of  phosphite  of  baryta  was 
formed  in  24  hours. 

Phosphate  of  Baryta. — Insoluble  in  water  and  formed  by  mixing  so- 
lutions of  muriate  of  baryta  and  phosphate  of  soda. 

Biphosphate  of  Baryta. — A  crystalline  salt,  with  an  acid  taste  and 
reaction  ;  obtained  by  Berzelius  by  dissolving  phosphate  of  baryta  in 
phosphoric  acid  and  evaporating  the  clear  solution. 


240  STRONTIUM. 

Berzelius  describes  three  other  phosphates  of  baryta. — Ann.  of  Phil 

xv.  277. 

Carbonate  of  Baryta.— Atom.  Num.  987  Symb.  (2O+C)+ 
(0+Ba.) 

Exceedingly  insoluble  in  distilled  water,  requiring  4300  times  its 
weight  of  water  at  60  ^  F.  and  2300  of  boiling  water  for  solution  ;  but 
when  recently  precipitated  it  is  dissolved  much  more  freely  by  a  solu- 
tion of  carbonic  acid  ;  is  highly  poisonous.  It  occurs  abundantly 
in  the  lead  mines"  of  the  north  of  England,  where  it  was  discovered  by 
Dr.  Withering,  and  has  hence  received  the  name  of  Witherite.  It  may 
be  prepared  by  way  of  double  decomposition,  by  mixing  a  soluble  salt 
of  baryta  with  any  of  the  alkaline  carbonates  or  bicarbonates. — See 
Parkes'  Chem.  Essays,  ii.  186. 

Selcniates  of  Baryta. — Selenic  acid  is  capable  of  uniting  with  baryta 
in  two  proportions.  The  neutral  salt  which  is  insoluble  consists  of 
100  acid-f-137  base  ;  the  biselcniate,  which  crystallizes  in  round  trans- 
parent grains,  and  is  soluble  in  water,  is  composed  of  100  acid-f-68 
base. — Henry,  i.  631. 

TESTS  OF  THE  SALTS  OF  BARYTA. — 1.  The  soluble  salts  of  baryta  are 
precipitated;  as  a  white  carbonate  of  baryta,  by  alkaline  carbonates,  and 
as  sulphate  of  baryta,  which  is  insoluble,  both  in  acid  and  alkaline  so- 
lutions, by  sulphuric  acid  or  any  soluble  sulphate.  2.  By  forming 
with  muriatic  acid  a  salt,  which  crystallizes  readily  by  evaporation  in 
the  form  of  four,  six  or  eight-sided  tables,  is  insoluble  in  alcohol,  and 
does  not  undergo  any  change  on  exposure  to  air. — See  Rose's  Manual 
of  Analytical  Chemistry. 

SECTION  V. 

STRONTIUM. 
Atom.  Num.  4&S—Symb.  Sr. 

Strontium  may  be  obtained  in  minute  quantiiies,  by  the  same  pro- 
cess as  barium,  substituting  the  carbonate  of  strontia,  which  is  a  na- 
tive product,  for  the  carbonate  of  baryta.  It  resembles  barium,  is  fusi- 
ble with  difficulty,  and  not  volatile.  It  decomposes  water  with  the 
evolution  of  hydrogen,  and  is  converted  into  an  oxide  by  exposure  to 
the  air. 

STRONTIUM    AND    OXYGEN. 

Protoxide  of  Strontium  or  Strontia. — Atom.  Num.  51 -S — 
Symb.   O+Sr. 

PROPERTIES.  A  gray  substance  with  a  pungent,  acrid  taste,  and 
when  powdered  in  a  mortar,  the  dust  that  rises  irritates  the  lungs  and 
nostrils  ;  resembles  baryta  in  appearance,  in  fusibility  and  in  possess- 


STRONTIUM.  241 

ing  distinct  alkaline  properties  ;  it  may  be  slaked  with  water  which 
causes  an  intense  heat. 

The  Hydrate  of  Strontia  fuses  readily  at  a  red1  heat,  but  the  water 
cannot  be  driven  off  by  the  strongest  heat  of  a  blast  furnace.  It  is 
very  soluble  in  boiling  water,  which  deposits  it  in  crystals  upon  being 
allowed  to  cool  undisturbed,  and  which  are  composed  according  to  Mr. 
Dalton  of  one  proportion  of  strontia  and  twelve  of  water. 

The  Solution  of  Strontia  has  a  caustic  taste  and  an  alkaline  re-action. 
Like  the  solution  of  baryta,  it  is^  a  delicate  test  of  the  presence  of  car- 
bonic acid  in  air  and  other  gaseo'us  mixtures,  forming  with  it  the  insol- 
uble carbonate  of  strontia. 

PREPARATION.  Strontia  can  be  obtained  by  exposing  the  metal  to 
air,  or  by  subjecting  the  nitrate  or  carbonate  of  strontia  to  a  strong  red 
heat. 

Peroxide  of  Strontium. — Atom.  Num.  59'S — Symb.  2O+Sr. 

A  white  substance,  of  a  brilliant  satiny  lustre,  inodorous  and  al- 
most tasteless.  It  is  formed  in  the  same  manner  as  the  corresponding 
preparation  of  barium,  and  also  by  pouring  an  aqueous  solution  of 
strontia  into  the  deutoxide  of  hydrogen. — For  details  and  preparation, 
See  Thcnard,  ii.  322. 

STRONTIUM    AND    CHLORINE. 

Chloride  of  Strontium.— Atom.  Num.  79-25—  Symb.  Cl+Sr. 

This  compound  is  formed  under  precisely  the  same  circumstances  as 
the  chloride  of  barium,  It  is  soluble  in  water,  and  is  then  converted 
into  a  Muriate  of  Kirontia,  which  crystallizes  in  long  slender  hexago- 
nal prisms,  which  are  soluble  in  two  parts  of  water  at  GO  ,  and  to 
almost  any  amount  in  boiling  water.  In  a  very  moist  atmosphere 
these  crystals  dsliquiate.  They  dissolve  in  alcohol  and  give  to  its 
-flame  a  blood-red  colour. 

Iodide  of  Strontium  may  be  obtained  in  the  same  manner  as  iodide 
of  barium.  Dissolved  in  water  and  carefully  evaporated,  it  furnishes 
delicate  prismatic  crystals,  of  Hydriodate  of  Strontia,  which,  when 
iieated  in  close  vessels,  fuse  and  become  iodide  of  Strontium  by  loss  of 
water. 

Sulphuret  of  Strontium  may  be  formed  by  fusing  strontia  and  sul- 
hur  in  a  green  glass  tube  :  or  by  exposing  the  powdered  sulphate  to 
a  red  heat  with  charcoal.  It  dissolves  in  water  with  the  same  phe- 
nomena as  the  sulphuret  of  potassium,  and  its  solution  furnishes,  by 
cautious  evaporation,  crystals  of  Hydrosulphuret  of  Strontia. 

SALTS    OF    STRONTIA. 

Chlorate  of  Strontia. — A  deliquescent  salt,  having  an  astringent 
taste,  and  detonating  when  thrown  upon  red  hot  coals  with  a  beautiful 
<purple  light  ;  formed  by  the  direct  action  of  chloric  acid  upon  carbon- 
ate of  Strontia. —  Vauqudin. 

lodate  of  Strontia. — A  difficultly  soluble  compound,  requiring  som 


242  STRONTIUM. 

hundred  parts  of  water  for  solution,  and  resolved  by  red  heat  into  oxy- 
gen, iodine  and  strontia. 

Nitrate  of  Strontia.— Atom.  Num.  105 -6— Symb.  (5O+N) 
+  (0+Sr.) 

PROPERTIES.  A  salt  crystallizing  in  octahedrons  or  irregular  prisms  ; 
soluble  in  its  own  weight  of  water  at  60J  F.,  or  in  little  more  than 
half  its  weight  of  boiling  water;  is  fused  at  a  red  heat  and  afterwards 
decomposed,  giving  out  oxygen,  nitrogen  and  gaseous  nitrous  acid, 
and  leaving  strontia  in  a  porous  mass.  When  the  crystals  are  applied 
to  the  wick  of  a  candle,  or  added  to  boiling  alcohol,  they  give  a  blood- 
red  colour  to  the  flame. 

PREPARATION.  This  salt  may  be  obtained  in  the  same  manner  as  the 
nitrate  of  baryta.  It  is  used  for  forming  the  red  fire. — See  Brandes 
Jour.  ix.  411,  and  Cuthbush's  Pyrotcchny. 

Sulphate  of  Strontia.— Atom.  Num.  91-8— Symb.   (3O+S) 
+(0+Sr.) 

PROPERTIES.  White,  tasteless,  of  a  specific  gravity  of  about  4;  fusi- 
ble at  a  high  temperature  ;  nearly  insoluble,  one  part  requiring  near- 
ly 4,000  of  water  for  its  solution,  when  heated  with  charcoal  is  decom- 
posed, and  sulphuret  of  strontium  is  formed. 

NATIVE  STATE  AND  PREPARATION.  This  salt  is  found  native  in  con- 
siderable quantities.  It  is  sometimes  of  a  blue  tint,  and  has  hence 
been  called  celestine.  Sometimes  it  is  colourless  and  transparent. — Its 
primitive  form  is  a  prism,  with  a  rhomboidal  base.  Fine  crystals  are 
found  on  Strontian  Island,  in  Lake  Erie. 

It  may  be  artificially  prepared  in  the  same  manner  as  the  sulphate  of 
baryta.  It  is  sometimes  used  as  a  flux. — Brande's  Jour.  vii.  183 

Phosphate  of  Strontia. — A  tasteless  salt,  insoluble  in  water,  but  soluble 
in  an  excess  of  phosphoric  acid  ;  fusible  by  the  blow-pipe  into  a  white 
enamel,  and  decomposable  by  sulphuric  acid ;  by  ignition  with  charcoal 
it  furnishes  Phosphuret  of  Strontium. 

It  is  formed  by  mixing  solutions  of  muriate  of  strontia  and  sulphate 
of  soda. 

Besides  this  salt,  there  is  also  a  Biphosphate,  consisting  of  two  atoms 
of  acid,  one  of  base,  and  two  of  water. 

Carbonate  of  Strontia. — This  compound,  which  occurs  native  at 
Strontian,  in  Argyleshire,  and  is  known  by  the  name  of  Strontianite, 
may  be  prepared  in  the  same  manner  as  carbonate  of  baryta.  It  is 
very  insoluble  in  pure  water,  but  is  dissolved  by  an  excess  of  carbonic 
acid. 

REFERENCES.  For  further  notices  of  the  salts  of  Strontia,  see  an  account 
of  the  Analysis  of  Stromeyer,  in  Brande's  Jour.  iii.  215;  and  in  Ann.  '.  of 
Ph  iv.  394— and  Thomson's  First  Prin.  ii.  285. 

TESTS  OF  THE  SALTS  OF  STRONTIA. — The  salts  of  strontia  resemble 
those  of  baryta  in  being  precipitated  by  sulphuric  acid  or  the  soluble 
sulphates.  Strontia  may  be  distinguished  from  baryta — 1.  By  its 
forming  with  muriatic  acid  a  salt  which  crystallizes  in  the  form  of 


CALCIUM.  243 

slender  hexagonal  prisms,  deliquesces  in  a  moist  atmosphere,  and  is 
very  soluble  in  pure  alcohol.  2.  The  alcoholic  solution  when  set  on 
fire  burns  with  a  deep  red  flame  ;  and  the  salts  of  strontia,  when  ex- 

rsed  to  the  blow-pipe  flame  on  platinum  wire,  impart  to  it  a  red  tinge. 
The   hydrofluosilisic  acid  precipitates  barytic  salts,  but  forms  with 
strontia  a  salt  very  soluble  in  slight  excess  of  the  acid.*  —  Berzelius, 
See  also   Roses  Manual  of  Analytical  Chemistry,    and  Henry's  Chem. 
ii.  58L     Andrews'  in  Phil.  Mag.  and  Ann.  vii.  404. 

SECTION   VL 

CALCIUM. 

Atom.  Num.  20  5  —  Sfym&.  Ca. 


First  obtained  by  Sir.  H.  Davy,  in  1808,  by  exposing  lime  to  the  ac- 
tion of  a  voltaic  battery, 

PROPERTIES.  Calcium  is  a  white  metal  having  the  lustre  and  co- 
lour of  silver,  and  which,  when  exposed  to  air  and  gently  heated,  is 
oxidized  and  converted  into  lime.  Its  other  properties  are  unknown. 
It  is  obtained  by  a  process  similar  to  that  employed  for  procuring  ba- 
rium. 

CALCIUM    AND    OXYGEN. 

Protoxide  of  Calcium  or  Lime.  —  Atom.  Num.  28*5  —  Symb.  O 
-f-Ca. 

PROPERTIES.  Colour  light  gray  ;  taste  acrid  and  caustic;  it  con- 
verts vegetable  blues  to  green  ;  specific  gravity  2-3  ;  very  difficult  of 
fusion,  but  remarkably  promotes  the  fusion  of  other  bodies,  and  is 
therefore  used  in  several  metallurgic  processes  as  a  cheap  and  power- 
ful flux;  it  can  only  be  fused  when  quite  pure  by  the  oxygen  blow- 
pipe or  by  the  voltaic  flame,  and  then  only  in  minute  particles  ;  when 
exposed  to  the  air  it  becomes  white  by  the  absorption  of  water  and  a 
little  carbonic  acid. 

Hydrate  of  Lime.—  Atom.  Num.  37'5  —  Smyb.   (O+Ca)+ 
(0+H.) 

The  combination  of  lime  with  water  is  attended  with  a  great  in- 
crease of  temperature  and  the  formation  of  a  white  bulky  hydrate.  — 


e 
po- 


* Mr.  Andrews  has  given  a  very  simple  method  of  detecting  the  presenc 
of  baryta  and  strontia  in  lime,  The  whole  is  dissolved  ifi  nitric  acid,  evapo 
rated  to  dryness,  and  the  acid  expelled  by  heating  to  redness  in  a  platinum 
crucible-  The  caustic  residue  is  boiled  with  water,  when  the  whole  of  the 
baryta  and  strontia  and  only  a  little  of  the  lime  are  dissolved.  Sulphuric  acid 
added  to  the  solution  shows  if  any  of  these  two  earths  are  present,  while  a 
boiling  saturated  solution  of  sulphate  of  strontia  troubles  it  if  it  contains  ba- 
ryta. but  causes  no  precipitate  if  the  earth  be  strontia.  —  Johnston's  Report  on 


Chemistry. 


244  CALCIUM. 

The  process  of  slaking  lime  consists  in  forming  this  hydrate,  and  the 
hydrate  itself  is  called  slaked  lime.  It  differs  from  the  preceding  hy- 
drates, in  parting  with  its  water  at  a  red  heat, — and  it  possesses  the 
singular  property  of  being  more  soluble  in  cold  water  than  in  hot  wa- 
ter.— Dalton. 

Lime  Water  is  prepared  by  mixing  hydrate  of  lime  with  water,  agi- 
tating the  mixture  repeatedly,  and  then  setting  it  aside  in  a  well-stop 
ped  bottle  until  the  undissolved  parts  shall  have  subsided.  The  sub- 
stance called  milk  or  cream  of  lime,  is  made  by  mixing  hydrate  of  lime 
with  a  sufficient  quantity  of  water  to  give  it  the  liquid  form  ;  it  is 
merely  lime-water  in  which  hydrate  of  lime  is  mechanically  suspend- 
ed. 

Lime-water  has  a  harsh  acrid  taste,  and  changes  vegetable  blues  to 
green  ;  it  has  a  strong  affinity  for  carbonic  acid,  and  forms  with  it  an 
insoluble  carbonate,  hence  lime-water  should  be  carefully  protected 
from  the  air — for  the  same  reason  also,  it  is  rendered  turbid  by  a  so-  ' 
lution  of  carbonic  acid  ;  but  on  adding  a  large  quantity  of  the  acid, 
the  transparency  of  the  solution  is  completely  restored,  because  car- 
bonate of  lime  is  soluble  in  excess  of  carbonic  acid. 

PREPARATION  OF  LIME.  The  ordinary  process  for  obtaining  lime, 
is  to  expose  common  lime-stone  (carbonate  of  lime)  to  a  strong  heat 
in  a  kiln ;  carbonic  acid  is  expelled  by  the  heat,  and  pure  lime,  called 
quicklime,  remains.  But  if  lime  of  great  purity  is  required,  it  should 
be  prepared  by  calcining,  in  a  crucible  for  several  hours,  Carrara  or 
Parian  marble,  or  carbonate  of  lime  which  has  been  precipitated  by 
carbonate  of  ammonia  from  the  muriate,  and  perfectly  edulcorated  by 
abundance  of  distilled  water. 

REFERENCES.  Gay  Lussac  on  the  crystallization  of  Lime,  Aim.  de  Chinv 
etdePhys.\.  334,  or  Ann.  of  Phil.  viii.  150.  R.  Phillips,  on  the  solution 
and  crystallization  of  Lime,  Ann.  of  Phil.  xvii.  107.  Dalton  on  the  solubili- 
ty of  Lime  in  cold  and  hot  ivater,  Brandos  Jour.  xi.  202.  Whijtt  on  the  va- 
rious strength  of  different  Lime-waters,  Edin.  Literary  Essays,  i.  420.  For 
details  concerning  the  manufacture  of  Lime,  see  Aikitfs  Dictionary. 

Peroxide  of  Calcium.— Atom.  Num.  3&5—Symb.  2O-fCa. 

When  oxygen  gas  is  passed  over  ignited  quick-lime  it  is  absorbed, 
and  a  portion  of  peroxide  of  calcium  is  formed.  A  similar  peroxide 
united  with  water,  is  formed  also,  according  to  Theriard,  when  lime  is 
brought  into  contact  with  the  deutoxide  of  hydrogen,  discovered  by 
that  chemist.— Traite  de  Chim.  ii.  320. 


CALCIUM  AND    CHLORINE. 

Chloride  of  Calcium. — Atom.  Num.  55*95 — Symb.  Cl+Ca. 

PROPERTIES.  Taste  bitter  and  acrid  ;  deliquesces  rapidly  upon  ex- 
posure to  the  air ;  is  soluble  in  a  very  small  quantity  of  water,  and  is 
then  converted  into  Muriate  of  Lime;  soluble  in  alcohol ;  when  fused 
it  acquires  a  phosphorescent  property,  as  was  first  observed  by  Hom- 
berg,  and  hence  called  Homberg's  Phosphorus. 

PREPARATION.  This  compound  may  be  prepared  by  heating  lime  in 
chlorine  gas ;  one  volume  of  chlorine  is  absorbed,  half  a  volume  of 


CALCIUM.  245 

oxygen  is  evolved,  and  a  chloride  of  calcium  is  formed.  It  may  also 
be  "formed  by  saturating  muriatic  acid  with  carbonate  of  lime,  evapo- 
rating to  dry  ness  arid  fusing  the  residue.  It  is  abundantly  produced  in 
the  manufacture  of  carbonate  of  ammonia,  from  the  decomposition  of 
muriate  of  ammonia  by  lime,  and  hence  has  sometimes  been  called 
Fixed  Sal  Ammoniac. 

USES.  On  account  of  the  great  affinity  of  this  compound  for  water, 
it  is  much  employed  to  deprive  gases  and  other  substances  of  their 
moisture.  It  is  also  used  for  forming  frigorific  mixtures  with  snow. 
[See  p.  53.] 

Chloride  of  Lime. 

This  compound  called  also  Oxymuriate  of  Lime  or  Bleaching  Pow- 
der, is  prepared  by  exposing  thin  strata  of  recently  slaked  lime  in  fine 
powder,  to  an  atmosphere  of  chlorine.  The  gas  is  absorbed  in  large 
quantity,  and,  according  to  some  chemists,  combines  directly  with  the 
lime.  Mr.  Dalton,  M.  Welter  and  Dr.  Thomson,  consider  the  bleach- 
ing powder  a  hydrated  subchlonde  or  dichloride  of  time,  containing  one 
proportion  of  chlorine  united  to  two  proportions  of  lime  ;  while  Dr. 
Ure  maintains  that  the  elements  of  this  compound  do  not  constitute  a 
regular  atomic  combination, — an  opinion  which  appears  to  be  entitled 
to  most  credit. 

PROPERTIES.  A  dry  white  powder,  which  smells  faintly  of  chlorine, 
and  has  a  strong  taste  ;  it  dissolves  partially  in  water,  the  solution 
possessing  strong  bleaching  powers,  and  being  gradually  decomposed 
by  exposure  to  the  atmosphere  ;  the  dry  powder  is  decomposed  by 
heat,  evolving  first  chlorine  and  afterwards  pure  oxygen  gas. 

TESTS.  The  most  convenient  process  for  estimating  the  value  of 
this  powder,  is  that  of  Welter's,  which  consists  in  ascertaining  the 
power  of  the  bleaching  liquid  to  deprive  a  solution  of  indigo  of  known 
strength  of  its  colour ;  and  directions  have  been  drawn  up  by  Gay 
Lussac  for  enabling  manufacturers  to  employ  this  method  with  accu- 
racy. [Ann  of  Phil.  xxiv.  218.]  For  anylitical  purposes,  the  best 
method  is  to  decompose  chloride  of  lime,  confined  in  a  glass  tube 
over  mercury,  by  means  of  muriatic  acid.  Muriate  of  lime  is  gener- 
ated, and  the  chlorine  being  set  free,  its  quantity  may  easily  be  meas- 
ured. 

USES.  This  compound,  first  prepared  by  Mr.  Tennant  of  Glasgow, 
is  now  extensively  employed  in  the  art  of  bleaching.  It  is  also  largely 
used  as  a  disinfecting  agent. 

REFERENCES.  For  Papers  on  the  nature  of  this  compound  by  Dalton, 
Welter,  Thomson,  and  Ure,  see  Ann.  of  Phil.  i.  15.  ii.  6.  xiii.  182.  xv.  401. 
Ann.  de  Chiin.  et  de  Phys.  viii.  Brandos  Jour,  xiii.  1.  Also,  Killimaii's 
Jour.  xiv.  251.  Ure's  Cheni.  Dictionary.  Labarraque  on  the  preparation  of 
Chloride  of  Lime,  Edin.  New  Phil.  Jour.  i.  320.  Tennanfs  Patent  for 
Bleaching  with  compounds  of  Chlorine  and  Lime,  SfC  ,  Repert.  of  Arts  \sl 
ser.  ix.  303.  And  for  farther  details  concerning  the  employment  of  tliis  pow- 
der, see  Parkes*  CJiemical  Essays,  iv.  I. — Cooper,  in  the-  Emporium  of 
Arts,  iii.  158.  The  Art.  Bleaching,  in  the  supplement  to  the  E din.  Eii cyclope- 
dia, and  BertholieCs  Work  on  the  same  subject. 


246  CALCIUM. 

CALCIUM    AND    IODINE. 

Iodide  of  Calcium. — Atom.  Num.   146-5 — Symb.  I+Ca. 

A  white  fusible  compound,  obtained  by  evaporating  to  dryness  the 
hydriodate  of  lime,  and  strongly  heating  the  residue;  when  dissolved 
in  water  it  is  again  converted  into  Hydriodate  of  Lime. 

CALCIUM    AND    FLUORINE. 

Fluoride  of  Calcium.— Atom.  Num.  39.18—  Symb.  F+Ca. 

SYN.     Fluate  of  Lime.     Fluor  or  Derbyshire  Spar. 

A  natural  product  found  in  many  parts  of  the  world,  and  often 
worked  into  ornaments  ;  when  crystallized  it  most  commonly  occurs 
in  cubes,  but  its  primitive  form  is  an  octahedron  ;  its  specific  gravity 
3-15  ;  is  tasteless  and  insoluble  in  water  ;  emits  a  phosphorescent 
light  when  thrown  upon  an  iron  plate  heated  below  redness  ;  evolves 
hydrofluoric  acid  when  acted  upon  by  concentrated  sulphuric  acid, 
but  is  not  decomposed  by  anhydrous  sulphuric  acid.  [See  p.  122.] 

CALCIUM    AND    SULPHUR. 

Sulphurct  of  Calcium. — Atom.  Num.  36-5 — Symb.  S-f-Ca. 

This  compound  was  formed  by  Berzelius  by  passing  sulphuretted 
hydrogen  gas  over  red  hot  lime,  the  oxygen  of  which  united  with  the 
hydrogen  to  form  water,  while  the  sulphur  united  with  the  calcium. — 
Berthier  formed  it  also  by  exposing  anhydrous  sulphate  of  lime  to  a 
strong  heat  in  a  charcoal  crucible. 

The  phosphorescent  substance  called  Canton's  Phosjriiorus,  which  is 
made  by  exposing  a  mixture  of  calcined  oyster-shells  and  sulphur  to  a 
red  heat,  is  supposed  to  be  a  sulphuret  of  lime  ;  but  its  real  composition 
has  not  been  determined. 

CALCIUM    AND    PHOSPHORUS. 

Phosphuret  of  Calcium. — Jltom.  Num.  36.2 — Symb.  P+Ca* 

When  the  vapour  of  phosphorus  is  passed  over  fragments  of  red 
hot  lime,  a  portion  of  phosphuret  of  calcium  is  formed,  mixed  with 
phosphate  of  lime  and  some  uncombined  phosphorus  and  lime.  This 
substance  was  formerly  regarded  as  a  phosphuret  of  lime,  but  there 
is  no  doubt  that  a  compound  of  phosphorus  with  the  metallic  base  is 
formed.  The  evidence  of  this  fact  is  that,  when  properly  prepared, 
it  decomposes  water,  and  liberates  phosphuretted  hydrogen,  which 
can  only  be  ascribed  to  the  action  of  calcium  upon  the  water.  [See 
p.  163.] 


CALCIUM.  247 


SALTS    OP    LIME. 

Chlorate  of  Lime  is  a  very  soluble  deliquescent  salt  of  a  sharp  bit- 
terish taste,  soluble  also  in  alcohol,  and  giving  out  oxygen  gas  when 
heated.  It  is  most  easily  produced  by  dissolving  carbonate  of  lime  in 
chloric  acid. 

lodate  of  Lime  is  difficultly  crystallizable  in  small  quadrangular 
prisms,  requiring  for  solution  several  hundred  times  its  weight  of  wa- 
ter :  when  exposed  to  a  strong  heat  it  is  decomposed,  oxygen  and 
iodine  are  given  off,  and  the  base  remains. 

Nitrate  of  Lime.— Atom.  Num.   109  5—Symb.  (5O+N)+ 
(O+Ca/H-3  aq. 

PROPERTIES.  Very  bitter  and  deliquescent ;  soluble  in  four  parts 
of  water  at  60°  F. ;  difficult  to  procure  in  regular  crystals,  but  when 
the  solution  is  boiled  down  to  the  consistence  of  a  syrup,  and  expos- 
ed in  a  cool  place,  long  prismatic  crystals  are  formed,  resembling  in 
their  disposition,  bundles  of  needles  diverging  from  a  common  cen- 
tre ;  when  calcined  to  a  certain  degree  it  acquires  the  property  of 
emitting  light  in  the  dark,  and  was  formerly  known  by  the  name  of 
Baldicin's  Phosphorus  ;  if  a  concentrated  solution  of  potassa  be  added 
to  a  saturated  solution  of  this  salt,  the  whole  becomes  a  solid  mass, 
because  the  lime  which  is  precipitated  absorbs  the  water  of  the  liquid. 

This  phenomenon  was  called  by  some  old  chemists,  the  chemica 
miracle.  Thenard,  Traite  de  Chim.  iii.  250. 

NATIVE  STATE  AND  PREPARATION.  This  salt  is  found  mixed  with 
nitrate  of  potassa,  in  caverns,  &c.  also  in  the  cement  of  old  buildings. 
It  is  prepared  artificially  by  treating  coarsely  powdered  carbonate  of 
lime  by  dilute  nitric  acid. 

Sulphite  of  Lime  is  a  white  powder,  soluble  by  excess  of  sulphurous 
acid  and  then  crystallizing  in  six-sided  prisms,  terminated  by  long  six- 
sided  pyramids.  It  is  formed  by  passing  sulphurous  acid  into  a  mix- 
ture of  lime  and  warm  water, 

There  is  also  a  Hyposulphite  of  Lime  and  a  Hydrosulphuret  of  Lime. 
These  compounds  have  been  examined  by  Mr.  Herschell. 

Sulphate  of  Lime.— Atom.  Num.  68-5—  Symb.  (30+S) 

+  (0+Ca.) 

PROPERTIES.  Destitute  of  taste  and  smell  ;  difficultly  soluble,  re- 
quiring 500  times  its  weight  of  cold  and  450  of  hot  water  ;  fusible  by 
a  moderate  heat,  and  after  calcination  absorbs  water,  becomes  hot  and 
sets  rapidly  ;  at  a  red  heat  parts  with  some  of  its  acid  ;  [Thomson] 
is  decomposed  by  the  alkaline  carbonates,  a  double  exchange  of  prin- 
ciples ensuing  ;  is  decomposed  also  by  ignition  with  charcoal. 

PREPARATION  AND  NATIVE  STATE.  This  salt  is  easily  formed  by  mix- 
ing a  solution  of  muriate  of  1-me  with  any  soluble  sulphate.  It  occurs 
abundantly  as  a  natural  production.  The  mineral  called  Anhydrite  is 
an  anhydrous  sulphate  of  lime  ;  and  all  the  varieties  of  Gypsum  are 
composed  of  the  same  salt,  united  with  water. 


248  CALCIUM. 

USES.  When  the  hydrous  salt  is  deprived  of  its  water  by  a  low  red 
heat,  it  forms  Plaster  of  Paris.  This  possesses  the  property  of  becom- 
ing hard  when  made  into  a  thin  paste  with  water,  owing  to  the  chem* 
ical  combination  of  the  anhydrous  sulphate  with  that  liquid.  Hence 
it  is  used  in  stucco  work  and  in  taking  casts,  busts.  &c.  Prof.  Emmet 
has  ascertained  that  raw  gypsum,  finely  pulverized,  is  capable  of  un- 
dergoing immediate  and  perfect  solidification,  when  mixed  with  certain 
solutions  of  the  alkali  potassa.  Among  those  that  answer  best,  may 
be  enumerated  caustic  potassa,  carbonate  and  bicarbonate,  sulphate  and 
bisulphate,  silicate  and  double  tartrate  or  Rochelle  salt.  [Sittiman's 
Jour,  xxiii.  209.]  The  common  gypsum  is  largely  employed  in  agri- 
culture. 

REFERENCES.  Thomson's  First  Prin.  ii.  293.  Thenard,  iii.  176.  Gay 
Lussac  on  the  setting  of  Plaster,  Franklin  Jour.  N.  S.  vii.  68. 

Sulphate  of  Soda  and  Lime,, — Occurs  native  in  the  form  of  transpa- 
rent crystals,  and  is  known  by  mineralogists  under  the  name  of  Gluu- 
berite. 

Phosphate  of  lAme.—Atom.  Num.  (tt-2—Symb.    (2JO+P) 
+(0+Ca.) 

PROPERTIES.  An  insipid  white  powder  ;  insoluble  in  water,  but  so- 
luble in  diluted  nitric,  muriatic  and  acetic  acids,  and  again  precipita- 
ble,  unaltered,  from  those  acids  by  caustic  ammonia  ;  at  a  high  tem- 
perature it  fuses  into  an  opake  white  enamel. 

PREPARATION  AND  NATIVE  STATE.  This  salt  is  the  principal  ingre- 
dient in  animal  bones,  of  which  it  constitutes  about  86  per  cent.  It 
may  be  obtained  by  dissolving  bones,  which  have  been  well  calcined 
and  then  pulverized,  in  dilute  muriatic  acid,  adding  ammonia  to  the 
solution  and  washing  and  drying  the  precipitate  ;  or  by  mixing  solu- 
tions of  phosphate  of  soda  and  muriate  of  lime.  It  is  also  found  na- 
tive in  the  mineral  kingdom. 

Biphosphate  of  Lime.— Atom.  Num.  99-9— -Symb.  2  (2JO+ 
P)+(0+Ca.) 

PROPERTIES.  A  white  deliquescent  uncrystallizable  mass,  which 
strongly  reddens  vegetable  blues,  and  dissolves  in  water  without  de* 
composition  ;  before  the  blow  pipe  it  melts  into  a  transparent  glass, 
insoluble  in  water. 

It  may  be  formed  by  digesting  phosphate  of  lime  with  a  quantity  of 
phosphoric  acid  equivalent  to  that  already  engaged  in  the  salt. 

Besides  the  above,  three  other  phosphates  are  described. — See  Hen- 
ry, i.  614. 

Carbonate  of  Lime. — Atom.  Num.  50*5 — Symb.  (2O+C.) 
+(0+Ca.) 

PROPERTIES.  Very  sparingly  soluble  in  pure  water,  but  is  dissolv- 
ed by  water  saturated  with  carbonic  acid;  it  is  decomposed  by  a 
strong  red  heat,  and  by  almost  all  the  acids,  giving  rise,  in  the  latter 


MAGNESIUM.  249 

i  case,  to  the  phenomenon  of  effervescence;  fusible  at  a  heat  of  about 
22°  of  Wedgewood's  pyrometer,  if  the  escape  of  the  carbonic  acid  is 
prevented  by  strong  pressure — [$ir  James  Hall  in  Nicholson  s  Jour. 
xiii.  and  xiv.]  and  by  the  sudden  application  of  a  violent  heat,  with- 
out additional  compression— [Bucholz,  Nicholson's  Jour.  xvii.  229  ;] 
is  decomposed  into  its  ultimate  elements  by  being  heated  with  phos- 
phorus.— Tcnnant,  in  Phil.  Trans,  for  1791. 

PREPARATION  AND  NATIVE  STATE.  Lime-water,  when  exposed  to  an 
atmosphere  of  carbonic  acid  becomes  soon  covered  with  a  crust  of 
carbonate  of  lime.  This  salt  may  also  be  obtained  by  adding  hydrate 
of  lime  to  any  of  the  carbonates  of  the  alkalies. 

Carbonate  of  lime  is  a  very  abundant  natural  production,  and  oc- 
curs, under  a  great  variety  of  forms  ;  such  as  calcareous  spar,  Iceland 
spar,  chalk,  marble  and  common  limestone. 

Bicarbonate  of  Lime — Exists  only  in  solution:  and  in  this  state  is 
often  found  in  mineral  waters.  If  a  current  of  carbonic  acid  is  passed 
through  lime  water,  the  solution  becomes  milky,  and  carbonate  of  lime 
is  precipitated ;  but  if  the  current  of  gas  be  continued,  the  solution 
again  becomes  transparent ; — the  bicarbonate,  thus  formed,  being  dis- 
solved by  the  water. 

Carbonate  of  Soda  and  Lime— A  mineral  occuring  at  Merida,  in 
South  America,  in  transparent  and  colourless  crystals.  It  was  named 
Gay-lussite,  in  honour  of  Gay  Lussac.  It  consists  of  1  atom  carbon- 
ate of  soda;  1  atom  carbonate  of  lime  and  11  atoms  of  water. — Berze- 
lius.  Trrtite  de  Chim.  iv.  78. 

Carbonate  of  Baryta  and  Lime, — found  native  in  Cumberland  (Eng.) 
and  known  by  the  name  of  baryto-caUite.  It  occurs  in  oblique  rhombic 
prisms,  translucent,  having  a  yellowish  brown  tinge,  and  consists  of  1 
atom  carbonate  of  baryta  and  1  atom  carbonate  of  lime. — Ann.  of  Phil. 
N.  S.  viii.  114. 

TESTS  OF  THE  SALTS  OF  LIME.  The  most  delicate  test  of  the  pre- 
sence of  lime  is  oxalate  of  ammonia  or  potassa  ;  for,  of  all  the  salts  of 
lime,  the  oxalate  is  the  most  insoluble  in  water.  This,  however,  will 
not  distinguish  lime  from  baryta  or  strontia  ;  for  this  purpose  the  best 
characters  are,  that  nitrate  of  lime  yields  prismatic  crystals  by  evapora- 
tion, is  very  deliquescent  and  very  soluble  in  pure  alcohol. 

The  salts  of  lime,  when  heated  before  the  blow -pipe,  or  when  their 
alcoholic  solutions  are  fired,  communicate  to  the  flame  a  dull  brownish 
red  colour. 

SECTION  VII. 

MAGNESIUM. 
Atom.  Num.  12-7— Symb.  Mg. 

The  existence  of  the  metallic  basis  of  magnesia  was  demonstrated  by 
Sir  H.  Davy,  but  the  metal  was  obtained  by  him  in  quantities  too  mi- 
nute for  determining  its  properties. 

Recently,  however,  M.  Bussy,  of  Paris,  has  procured  this  metal  by 
the  decomposition  of  the  chloride,  by  a  process  similar  to  that  em- 
ployed by  M.  Wb'hler,  (see  the  next  section.) 

According  to  Bussy,  magnesium  is  brilliant,  silvery  white,  perfectly 


250  MAGNESIUM. 

ductile  and  malleable,  fusible  at  a  moderate  temperature,  like  zinc 
volatilized  at  a  temperature  a  little  higher  than  that  of  its  melting  point, 
and,  like  that  metal,  condenses  in  small  globules  ;  it  does  not  decompose 
water  at  common  temperatures  ;  it  oxidizes  at  a  high  temperature,  and 
is  slowly  converted  into  magnesia,  when  in  small  masses,  but  when  in 
filings,  it  burns  with  great  splendour,  throwing  out  sparks,  like  iron  in 
oxygen. — Phil.  Mag.  and  Ann.  vii.  389. 

MAGNESIUM    AND    OXYGEN. 

Oxide  of  Magnesium  or  Magnesia. — Jltom.  Num.  2O7 — 
Symb.  O+Mg. 

PROPERTIES.  A  white  insipid  friable  powder,  of  an  earthy  appear- 
ance, slightly  greening  the  blue  of  violets ;  specific  gravity  2-3  ;  al- 
most infusible  and  very  sparingly  soluble  in  water  ;  it  absorbs  carbonic 
acid  from  the  air  at  ordinary  temperatures  ;  has  a  weaker  affinity  than 
lime  for  water,  for  though  it  forms  a  hydrate  when  moistened,  the  com- 
bination is  effected  with  hardly  any  disengagement  of  caloric,  and  the 
product  is  readily  decomposed  by  a  red  heat. 

There  probably  exist  several  different  compounds  of  water  and  mag- 
nesia, but  the  native  hydrate  is  the  only  one  known  with  certainty. — 
This  occurs  at  Hoboken,  in  New-Jersey. 

NATIVE  STATE  AND  PREPARATION.  Magnesia  is  by  no  means  a  rare 
production  of  nature  ;  for  though  very  seldom  found  in  a  state  ap- 
proaching to  purity,  yet  it  enters  largely  into  some  rocks  that  com- 
pose extensive  formations,  such  as  serpentine,  steatite,  &c.,  and  in 
combination  with  sulphuric  and  muriatic  acids,  it  forms  a  large  pro- 
portion of  the  ingredients  of  sea-water.  Its  principal  use  is  in  medi- 
cine. 

Magnesia  is  artificially  prepared  by  exposing  carbonate  of  magne- 
sia to  a  strong  red  heat,  by  which  carbonic  acid  is  expelled.  This 
forms  what  is  called  in  the  shops,  Calcined  Magnesia,  the  purity  of 
which  can  be  tested  by  a  small  quantity  of  sulphuric  acid ;  if  effer- 
vescence ensues,  we  infer  that  carbonic  acid  is  not  entirely  expel- 
led. According  to  Mr.  Donovan,  during  the  ignition  of  magnesia  a 
bright  white  light  is  emitted  by  the  earth,  apparently  of  the  phosphoric 
kind  ;  a  phenomenon  which  also  attends  the  ignition  of  some  other 
earths. 

Chloride  of  Magnesium  may  be  obtained  by  passing  chlorine  over 
red  hot  magnesia  ;  but  an  easier  process,  suggested  by  Liebig,  is  to 
mix  equal  weights  of  dry  muriate  of  magnesia  and  sal-ammoniac,  and 
project  the  mixture  in  successive  portions  into  a  platinum  crucible 
kept  at  a  red  heat.  When  the  ammoniacal  salt  is  wholly  expelled,  the 
fused  chloride  of  magnesium  is  left  in  a  state  of  tranquil  fusion,  and 
on  cooling  becomes  a  transparent  colourless  mass  which  is  highly  deli- 
quescent, and  is  very  soluble  in  alcohol  and  water.  It  is  b_y  the  action 
of  potassium  on  this  compound,  that  the  metal  magnesium  is  most 
conveniently  obtained. 

This  compound  when  exposed  to  the  air  is  converted  into  muriate  of 
magnesia,  a  salt  which  forms  one  of  the  ingredients  of  sea  water. 

A  compound,  called  Chloride  of  Magnesia,  is  prepared  by  passing 
chlorine  gas  into  water  in  which  magnesia  is  kept  mechanically  sus- 
pended, or  by  a  mixture  of  solutions  of  chloride  of  lime  and  sulphate 


MAGNESIUM.  251 

of  magnesia.  It  hag  not  yet  been  accurately  investigated.  It  has  been 
used  with  advantage  in  some  of  the  processes  of  bleaching  and  calico- 
printing.  —He nry,  i.  368. 

SALTS    OF    MAGNESIA. 

Nitrate  of  Magnesia.— Atom.  Num.  123-7— Symb.  (5O+N) 
+ (0+Mg)+6  aq. 

PROPERTIES.  Very  bitter,  deliquescent,  and  very  soluble  in  water  ; 
crytallizes  in  small  needles  and  sometimes  in  rhomboidal  prisms  ;  most 
commonly,  however,  it  forms  a  shapeless  mass  ;  when  exposed  to  the 
heat  of  ignition,  it  fuses,  a  few  bubbles  of  oxygen  gas  first  escape,  and 
the  nitric  acid  then  passes  undecomposed. 

This  salt  which  also  occurs  in  nature,  may  be  artificially  prepared  by 
dissolving  carbonate  of  magnesia  in  dilute  nitric  acid,  and  evaporating 
the  solution. 

Sulphate  of  Magnesia.— Atom.  Num.  1237—  Symb.  (3O+S) 
+(0+Mg)+7  aq. 

PROPERTIES.  Taste  saline,  bitter,  and  nauseous ;  it  crystallizes 
readily  in  small  quadrangular  prisms,  which  effloresce  slightly  in  a  dry 
air,  and  is  obtained  also  in  larger  crystals,  which  are  irregular  six-sided 
prisms,  terminated  by  six-sided  summits  ;  its  primary  form  is  a  right 
rhombic  prism,  the  angles  of  which  are  90°  30'  and  89°  30',  (Brooke}; 
the  crystals  are  soluble  in  an  equal  weight  of  water  at  60°,  and  iri 
three-fourths  of  their  weight  of  boiling  water, — undergo  the  watery 
fusion  when  heated,  and  the  anhydrous  salt  is  deprived  of  a  portion  of 
its  acid  at  a  white  heat. 

NATIVE  STATE  AND  PREPARATION.  This  sulphate,  generally  known 
by  the  name  of  Epsom  Salt,  is  frequently  contained  in  mineral  springs, 
It  may  be  made  directly,  by  neutralizing  dilute  sulphuric  acid  with  car- 
bonate of  magnesia  ;  but  it  is  procured  for  the  purposes  of  commerce 
by  the  action  of  dilute  sulphuric  acid  on  magnesian  limestone,  the  na- 
tive carbonate  of  lime  and  magnesia. 

There  is  also  a  Hyposulphite  and  a  Sulphite  of  Magnesia. 

REFERENCES.  Longcliamp's  experiments  on  Sulphate  of  Magnesia,  Ann. 
ds  Chim.et  de  Phijs.  xii.  255,  or  Ann.  of  Phil.  xvi.  44.  Holland's  account 
of  the  manufacture  of  Sulphate  of  Magnesia,  at  Monte  de  la  Guardia,  near 
Genoa,  PhiL  Trans.  1816 — Arm.  of  Phil.  viii.  61.  Mojon,  on  the  same  sub- 
ject, Jour,  de  Phys.  or  Repert.  of  Arts,  2d  ser.  v.  392. 

Sulphate  of  Ammonia  and  Magnesia  may  be  obtained  by  mixing  so- 
lution of  sulphate  of  ammonia  with  solution  of  sulphate  of  magnesia  ; 
in  which  case,  one  part  only  of  the  magnesia  is  thrown  down,  the  re- 
mainder forming  with  the  sulphate  of  ammonia  this  triple  salt,  which 
crystallizes  in  octahedrons. 

By  a  similar  process  triple  sulphates  of  soda  and  magnesia,  and  of 
potassa  and  magnesia,  may  ba  formed.— Thomson's  First  Prin.  ii. 


252  MAGNESIUM. 

Phosphate  of  Magnesia. — A  salt  crystallizing  in  flat  four-sided  prisms, 
which  effloresce  in  the  air.  It  is  formed  by  the  direct  union  of  its  con- 
stituents, or  by  mixing  solutions  of  sulphate  of  magnesia  and  phosphate 
of  soda. — Thomson's  First  Prin.  ii.  304. 

Phosphate  of  Ammonia  and  Magnesia  or  Ammonio -phosphate  of  Mag- 
nesia.— This  salt  usually  occurs  in  the  form  of  a  white  insoluble  pow- 
der; but  in  certain  varieties  of  urinary  calculi,  it  is  found  lining  ca- 
vities in  a  distinctly  crystallized  form,  and  is  deposited  in  crystals  on 
the  sides  of  vessels  in  which  urine  has  been  long  kept;  it  is  tasteless 
—  scarcely  soluble  in  water— readily  soluble  in  dilute  acids,  and  is  de- 
composed by  heat,  leaving  phosphate  of  magnesia  only. 

This  salt  may  be  prepared  by  mixing  solutions  of  phosphate  of  am- 
monia and  phosphate  of  magnesia,  or  any  other  soluble  salt  with  a 
base  of  that  earth.  Dr  Wollaston  availed  himself  of  the  formation  of 
this  triple  salt,  to  separate  magnesia  from  other  earths.  It  consists, 
according  to  Dr.  Thomson,  of  one  atom  of  phosphate  of  ammonia-)- 
one  atom  phosphate  of  magnesia-)- four  water. — f  irst  Prin.  ii.  425. 

Carbonate  of  Magnesia. — A  torn.  Num.  42'5 — Symb.  (2O+C) 
+(0+Mg.) 

A  salt  occurring  native  in  great  abundance  in  Hindostan,  and  also 
at  Hoboken,  New-Jersey,  in  veins  in  a  serpentine  rock,  accompany- 
ing the  native  hydrate.  Its  colour  is  snow-white  ;  its  specific  gravity 
2-73  ;  it  is  rather  harder  than  fluor  spar,  and  it  dissolves  very  slowly 
in  acids,  unless  it  be  reduced  to  powder,  and  the  action  of  acids  pro- 
moted by  heat. 

The  artificial  carbonate  of  magnesia,  Magnesia  Alba  of  the  shops, 
varies  considerably  in  its  composition.  Berzelius  has  shown  that  the 
composition  is  regulated  by  the  quantity  of  water  employed,  and  by 
the  temperature  ;  for  the  powder  is  obtained  by  precipitating  the  sul- 
phate and  muriate  of  magnesia,  with  an  alkaline  carbonate.  He  is  of 
opinion  that  this  is  a  compound  of  three  atoms  of  carbonate  of  mag- 
nesia, with  one  atom  of  the  quadro-lrydrate  of  the  same  earth. — Thom- 
son's First  Prin.  ii.  303. 

This  compound  requires  2493  parts  of  cold,  and  9000  of  hot  water 
for  solution.  It  is  so  soluble  in  an  excess  of  carbonic  acid,  that  the 
sulphate  of  magnesia  is  not  precipitated  at  all  in  the  cold  by  the  alka- 
line bicarbonates,  or  by  the  sesquicarbonate  of  ammonia.  On  allow- 
ing a  solution  of  carbonate  of  magnesia  in  carbonic  acid  to  stand  in 
an  open  vessel,  minute  crystals  are  deposited,  which  consist  of  42 
parts  or  one  proportion  of  the  carbonate,  and  27  parts  or  three  propor- 
tions of  water. 

REFERENCES.  Berzelitis,  in  Ann.  of  Phil.  xii.  306.  Henn/s  Chem.  ii. 
641. 

Carbonate  of  Magnesia  and  Potassa  is  described  by  Berzelius,  Edin. 
Phil.  Jour.  ii.  66. 

Biborate  of  Magnesia. — This  salt  occurs  in  small  irregular  crystals, 
sparingly  soluble  in  water,  but  soluble  in  acetic  acid.  It  is  found  na- 
tive in  a  mineral  called  Boracite,  hitherto  found  only  near  Luneburg,  in 
Germany.  It  may  be  prepared  artificially  by  dissolving  magnesia  in 
boracic  acid — Thomson' s  First  Prin.  ii.  304. 


MAGiNESIUM.  253 

TESTS  OF  THE  SALT  OF  MAGNESIA.  Most  of  the  salts  of  magnesia  are 
soluble,  and  when  the  solutions  are  neutral,  white  precipitates  are  pro- 
duced upon  the  addition  of  pure  ammonia  and  carbonate  of  potassa. — 
When  the  solutions  are  acid,  'they  are  distinguished  from  solutions  of 
potassa,  soda  and  ammonia  salts,  by  producing  a  white  precipitate 
with  a  solution  of  phosphate  of  soda,  after  having  been  supersaturated 
with  ammonia.  They  are  distinguished  from  solutions  of  lithia  salts, 
by  affording  a  precipitate  with  an  excess  of  potassa,  particularly  when 
the  mixture  is  boiled.  From  solutions  of  baryta  andstrontia,  they  are 
distinguished  by  affording  no  precipitate  with  diluted  sulphuric  acid  ; 
and  from  solutions  of  lime,  by  their  relation  towards  oxalic  acid. — 
Rose's  Manual  of  Analyt.  Chem. 

For  further  information  concerning  the  separation  of  lime  and  mag- 
nesia, see  Phillips,  in  Brande's  Jour.  vi.  316 ;  Cooper,  same  icork,  vii. 
392;  Daubeny,  Edin.  PhU.  Jour.  vii.  108;  Brande's  Manual;  Henry's 
Ckem.  ii.  582. 


254  ALUMINUM. 

CLASS  III. 

METALS    WHICH  WHEN    COMBINED  WITH  OXYGEN  FORM    EARTHS, 
SECTION    VIK. 

ALUMINUM. 

Atom.  Num.  13-7—  Symb.  A  I. 

The  existence  of  the  metallic  basis  of  alumina  was  first  rendered 
probable  by  Sir  H.  Davy.  But  it  is  to  Wb'hler  that  we  are  indebted 
for  having  first  exhibited  it  in  a  metallic  state,  by  a  process  suggested 
by  Oersted. 

PROPERTIES.  This  metal  as  prepared  by  Wb'hler,  is  a  grey  powder, 
of  a  tin  white  colour,  especially  when  compressed  in  a  mortar  and 
rubbed  with  a  burnisher ;  its  aspect  is  decidedly  metallic  ;  it  is  infu- 
sible at  the  heat  at  which  cast  iron  melts  ;  it  does  not  conduct  elec- 
tricity, but  this  is  probably  owing  merely  to  its  pulverulent  form, 
which  deprives  other  metals  of  that  property,  though  they  decidedly 
possess  it  in  mass  [Henry,  i.  651.];  heated  to  redness  in  the  air,  it 
takes  fire,  and  burns  with  great  brilliancy  into  white  and  tolerably  hard 
alumina ;  when  introduced  red  hot  into  oxygen  gas  it  burns  with  a 
splendour  which  the  eye  can  hardly  support,  and  with  so  much  heat 
that  the  resulting  alumina  is,  in  part  at  least,  fused  into  yellow  frag- 
ments, which  are  as  hard  as  corundum,  and  not  only  scratch,  but  ab- 
solutely cut  glass ;  it  is  scarcely  acted  on  by  water  ;  is  acted  on  by 
hot  sulphuric  acid,  and  by  diluted  sulphuric  and  muriatic  acids,  and 
soluble  also  in  solutions  of  potassa  and  ammonia. 

PREPARATION.  The  process  for  preparing  this  metal  consists  in 
mixing  the  chloride  of  aluminum  with  potassium,  and  heating  the 
mixture  in  a  small  porcelain  or  platinum  crucible,  the  cover  of  which 
is  fixed  to  it  by  iron  wire.  Intense  heat  is  developed  during  the  action, 
the  crucible  though  but  gently  heated  externally  becoming  suddenly  red 
hot.  When  the  crucible  is  quite  cold,  it  is  put  into  a  large  glass  of 
water  in  which  the  saline  matter  is  dissolved,  with  slight  disengage- 
ment of  hydrogen  gas,  of  an  offensive  odour  ;  and  a  gray  powder  sep- 
arates, which  on  close  inspection,  especially  in  sunshine,  is  found  to 
consist  solely  of  minute  scales  of  metal.  After  being  washed  with 
cold  water,  it  is  pure  aluminum. 

REFERENCES.  Oersted,  in  Phil.  Mag.  and  Ann.  if.  391.  Wohlcr,  in  the 
same  work,  iv.  147,  or  Edin.  Jour,  of  Science,  ix.  177. 


ALUMINUM  255 

ALUMINUM    AND    OXYGEN. 

Oxide  of  Aluminum  or  Alumina. — Atom.  Nwn.  25-7 — Symb. 
1JO+  Al. 

PROPERTIES.  When  pure,  this  substance  has  neither  taste  nor  smell, 
and  does  not  affect  the  colours  of  vegetables  ;  it  is  not  soluble  in  wa- 
ter, but  when  moistened  with  that  fluid  forms  a  cohesive  ductile  mass  ; 
has  a  strong1  affinity  for  moisture,  and  after  ignition  greedily  absorbs 
it  from  the  atmosphere,  to  the  amount  of  half  its  weight;  it  is  capable 
of  combining  both  with  the  fixed  alkalies  and  with  acids,  but  is  very 
sparingly  taken  up  by  the  volatile  alkali,  and  not  at  all  by  the  alka- 
line carbonates  ;  it  has  a  strong  affinity  for  colouring  matter,  and  is 
much  used  in  the  processes  of  dyeing  and  calico  printing. 

It  ski-inks  in  bulk  when  exposed  to  heat. — On  this  property  is  founded 
the  Pyrometer  of  Mr.  Wedgewood,  which  measures  high  degrees  of 
heat,  by  the  amount  of  contraction  of  regularly  shaped  pieces  of  Chi- 
na clay.  This  instrument,  however,  is  not  an  accurate  measure  of 
heat,  since  the  contraction  of  clay  is  influenced  not  merely  by  the  de- 
gree of  heat  to  which  it  is  exposed,  but  by  the  mode  of  its  application. 
Henry  i.  654. 

NATIVE  STATE  AND  PREPARATION.  Alumina  is  most  abundantly  dis- 
tributed in  the  mineral  kingdom  of  nature.  It  is  found  nearly  in  a 
state  of  purity  in  the  precious  gems,  the  ruby  and  the  sapphire ;  and 
is  a  constituent  of  the  oldest  rocks  and  the  most  recent  alluvial  de- 
position. The  different  kinds  of  clay,  of  which  porcelain,  pipes 
and  bricks  are  made,  consist  of  the  hydrate  of  alumina,  in  various  de- 
grees of  purity.  It  may  be  obtained  free  from  the  admixture  of  other 
earths,  for  chemical  purposes,  by  precipitating  a  solution  of  alum  in 
water,  by  ammonia  or  the  carbonates  of  the  fixed  alkalies  ;  a  white 
bulky  hydrate  of  alumina  is  thus  obtained,  which  when  carefully  wash- 
ed and  heated  to  whiteness,  affords  the  pure  anhydrous  earth.  An  easi- 
er process,  proposed  by  Gay  Lussac,  is  to  expose  the  sulphate  of  alu- 
mina and  ammonia  to  a  strong  heat,  so  as  to  expel  the  ammonia  and 
the  sulphuric  acid. — Ann.  de  Chint.  et  de  Phys.  v.  101. 

There  are  probably  several  different  Hydrates  of  Alumina.  See 
Thomson's  First  Prin.  i.  315,  and  Bcrzelius,  ii.  369. 

ALUMINUM    AND    CHLORINE. 

Chloride  of  Aluminum. — Atom.  Num.    49-15 — Sijmb. 
C1+A1. 

PROPERTIES.  Colour  pale  greenish-yellow,  partially  translucent  and 
of  a  highly  crystalline  Jamellated  texture — somewhat  like  talc,  but 
without  regular  crystals  ;  it  fumes  slightly  when  exposed  to  the  air, 
emitting  an  odour  of  muriatic  acid  gas  and  deliquescing  into  a  clear 
liquid  ;  when  thrown  into  water  is  speedily  dissolved  with  a  hissing 
noise,  and  so  much  heat  is  evolved  that  the  water,  if  in  small  quantity, 
is  brought  into  a  state  of  brisk  ebullition,  and  the  solution  is  common 
Muriate  of  Alumina. 

PREPARATION.  This  chloride  may  be  produced  by  the  direct  com- 
bination of  its  two  ingredients  ;  but  it  may  be  more  easily  obtained  by 


256  ALUMINUM. 

calcining  pure  alumina  intimately  mixed  up  with  sugar  and  oil,  and 
passing  chlorine  over  the  mixture  at  a  red  heat.  The  charcoal  of  the 
sugar  and  the  oil  abstract  the  oxygen  of  the  alumina,  and  carbonic 
oxide  is  formed  ;  the  aluminum  at  the  same  time  unites  with  the  chlo- 
rine.—  Wohler,  Phil.  Mag.  and  Ann.  iv.  147. 

Sulphuret  of  Aluminum. — A  vitrified  semi-metallic  mass  which  ac- 
quires an  iron-black  metallic  lustre,  when  burnished.  It  is  formed  by 
dropping  a  piece  of  sulphur  on  aluminum,  when  strongly  incandescent, 
so  that  it  may  be  enveloped  in  an  atmosphere  of  the  vapour  of  sulphur 
— the  union  being  effected  with  vivid  emission  of  light. 

Phosphuret  of  Aluminum. — A  blackish  gray  pulverulent  mass,  which 
by  friction  acquires  a  dark  gray  metallic  lustre,  and  in  the  air  smells  in- 
stantly of  phosphuretted  hydrogen  It  is  formed  by  heating  aluminum 
to  redness  in  contact  with  the  vapour  of  phosphorus. 

Seleniuret  of  Aluminum. — A  black  pulverulent  substance  assuming  a 
dark  metallic  lustre  when  rubbed,  and  emitting  in  the  air,  a  strong 
odour  of  seleniuretted  hydrogen.  It  is  formed  with  the  disengage- 
ment of  heat  and  light,  by  heating  to  redness,  a  mixture  of  selenium 
and  aluminum. —  Wohler,  in  the  paper  above  quoted. 

SALTS    OP    ALUMINA. 

Nitrate  of  Alumina  may  be  formed  by  dissolving  fresh  precipitated 
alumina  in  nitric  acid.  The  solution,  which  is  always  acid,  crystal- 
lizes in  thin  ductile  plates.  The  crystals  are  extremely  soluble,  and 
are  deliquescent.  When  dried  by  pressure  between  folds  of  blotting 
paper,  Dr.  Thomson  finds  them  to  consist  of  1  atom  of  nitric  acid,  2 
atoms  of  base  and  10  of  water.  He  calls  it  a  Dinitrate.  By  a  stronger 
heat,  it  loses  a  portion  of  acid,  and  is  then  converted  into  what  he  calls 
a  Tris nitrate.—  First  Prin.  ii.  312. 

Sulphate  of  Alumina.— Atom.  Num.  1287—  Symb.  (3O+S) 
+  (Oi+Al)+7aq. 

PROPERTIES.  White,  very  styptic,  reddens  vegetable  blues  ;  it  usu- 
ally occurs  in  the  form  of  a  semi-transparent  mass,  but  is  with  difficul- 
ty crystallized.  It  may  be  obtained  by  digesting  sulphuric  acid  over 
hydrate  of  alumina. 

"There  is  also  a  Subsulphate  of  Alumina,  known  to  mineralogists  by 
the  name  of  Aluminite,  a  fine  white  mineral,  found  in  Sussex,  in  Eng- 
land, and  in  other  places  ;  it  is  called  by  Dr.  Thomson,  Trisulphate  of 
Alumina. — First  Prin.  ii.  311. 

Sulphate  of  Alumina  and  Potassa. 

SYN.     Alum.     Potash — Sulphate  of  Alumina — Thomson. 

PROPERTIES.  Taste  sweetish  and  astringent  ;  crystallizes  in  regular 
octahedrons  ;  dissolves  in  five  parts  of  water,  at  60°  F.  and  in  little 
more  than  its  own  weight  of  boiling  water ;  reddens  the  blue  of  lit- 
mus ;  exposed  to  heat  the  crystals  swell  up  and  become  a  dry  massr 
called  Burnt  Alum,  [Alumen  Ustum  of  the  Pharmacopeia]  ;  it  loses  a 
part  of  its  acid  at  a  red  heat.  According  to  Dr.  Thomson  the  crystal- 
line salt  consists  of  3  atoms  sulphate  of  alumina-j-1  atom  sulphate  of 


GLUCINUM.  257 

potassa-f-25  atoms  water==509'25.  But  according  to  Berzelius  the 
composition  may  be  thus  stated,  viz  :  2  atoms  sesqui-sulphate  of  alumi- 
na-f  1  atom  sulphate  of  potassa-j-24  atoms  water  =474 -55. 

PREPARATION.  This  salt  is  usually  prepared  by  roasting  and  lixivi- 
ating certain  clays  containing  pyrites  ;  to  the  leys  a  certain  quantity 
of  potassa  is  added,  and  the  triple  salt  is  obtained  by  crystallization. 
It  is  extensively  used  in  the  arts,  more  especially  in  dyeing  and  calico 
printing,  in  consequence  of  the  attraction  which  alumina  has  for  the 
colouring  matter.  It  also  forms,  when  ignited  with  charcoal,  a  spon- 
taneously inflammable  compound,  which  has  long  been  known  under 
the  name  of  Homberg's  Pyrophorus. 

REFERENCES.  A  memoir  on  Alum,  by  Dr.  T.  R.  Beck,  in  the  Transac- 
tions of  the  Soc.  of  Useful  Arts  of  the  State  of  New-  York,  iv.  part  if.  50, 
containing  a  detailed  account  of  its  history,  manufacture,  uses,  fyc.  The  art. 
Alum,  in  the  Supplement  to  the  Encyclopedia  Britannica,  by  Dr.  Thomson. 
Dr.  Coxe,  on  Hombergh's  Pyrophorus,  Ann.  of  Phil.  i.  68.  Hare  on  Pyro- 
phorus, Sitlimari's  Jour.  x.  36t>.  Gay  Lussac  on  the.  same  subject,  Ann.  de 
Chim.  et  de  Phys.  xxxvii.  415,  or  Branded  Jour.  N.  S.  iv.  207.  * 

Sulphate  of  alumina  forms,  with  sulphate  of  ammonia  and  with  sul- 
phate of  soda,  double  salts,  which  are  very  analogous  to  common  alum. 
—Riffault,  Ann.  dc  Chim.  et  de  Phys.  ix.  106.  Ann.  of  Phil.  xvii.  72. 
Beatson,  Brandes  Jour.  viii.  386.  Thomson's  First  Prin.  ii. 

TESTS  OF  THE  SALTS.  Alumina  may  be  recognized  as  follows :  1 . 
It  is  separated  from  acids  as  a  hydrate,  by  all  the  alkaline  carbonates, 
and  by  pure  ammonia.  2.  It  is  precipitated  by  pure  potassa  or  soda, 
but  the  precipitate  is  completely  redissolved  by  an  excess  of  the  alkali. 

SECTION  IX. 
GLUCINUM. 

Atom.  Num.  17-7 — Symb.  G. 

The  metallic  basis  of  glucina  was  first  obtained,  in  a  separate  state, 
by  Wbhler. 

PROPERTIES.  A  dark  gray  powder,  resembling  in  all  respects,  a  me 
tal  precipitated  in  the  pulverulent  form  ;  under  the  burnisher,  it  as- 
sumes a  dull  metallic  lustre  ;  its  fusing  point  is  very  high  ;  it  under- 
goes no  change,  either  in  air  or  when  exposed  to  boiling  water; 
when  heated  to  redness  on  platinum  foil,  it  takes  fire,  and  burns  with 
great  brilliancy,  and  glucina  is  regenerated ;  in  oxygen  it  burns  with 
extraordinary  brilliancy,  and  yet  the  glucina  formed  gives  no  indica- 
tions of  fusion  ;  it  burns  also  in  chlorine,  and  in  the  vapours  of  bro- 
mine and  iodine, 

PREPARATION.  The  process  of  Wohler  consists  in  subjecting  chlo- 
ride of  glucinum  to  heat,  in  contact  with  potassium,  in  a  platinum 
crucible. —  JVohler,  Ann.  de  Chim.  et  de  Phys.  xxxix.  77,  or  Phil.  Mag. 
<wd  Mnn.  v.  392, 


258  YTTRIUM. 


GLUCINUM    AND    OXYGEN'. 

Oxide  of  Glucinum  or  Glucina. — Atom.  Num.  25*7 — Symh. 
0-fG. 

Discovered  by  Vauquelin,  in  1798. 

PROPERTIES.  A  white  powder,  which  has  neither  taste  nor  odour, 
and  is  quite  insoluble  in  water  ;  specific  gravity  3  ;  it  does  not  affect 
vegetable  colours ;  forms,  with  aeids,  salts  having  a  sweetish  taste,  a 
circumstance  which  distinguishes  glucina  from  the  other  earths,  and 
from  which  its  name  is  derived  ;  it  is  soluble  in  liquid  potassa  or  so- 
da, but  not  in  a  solution  of  ammonia  ;  it  is,  on  the  other  hand,  com- 
pletely taken  up  by  carbonate  of  ammonia,  and  is  precipitated  from  it 
by  boiling,  a  property  which  distinguishes  it  from  other  earths  with 
which  it  might  be  confounded. 

NATIVE  STATE  AND  PREPARATION.  This  earth  has  been  ascertained 
to  exist  only  in  three  rare  minerals,  viz.  the  beryl,  the  emerald  and  the 
euclase.  It  is  commonly  prepared  from  beryl. — See  Berzelius,  TraiU 
de  Chim.  ii.  376.  Also,  Turner  and  Henry's  Chem. 

Berzelius  describes  a  Sulpkuret  and  a  Phosphuret  of  Gludnum,  ob- 
tained by  heating  the  metal  in  the  vapour  of  sulphur  or  phosphorus. 

SECTION  X. 
YTTRIUM. 

Atom.  Num.  32-2— Sy ml.  Y. 

The  base  of  yttria  has  been  extracted  by  Wohler,  in  a  manner  simi- 
lar to  that  employed  for  separating  glucinum  ;  but  there  appears  to  be 
much  more  difficulty  in  obtaining  yttrium  pure.  The  heat  developed 
by  the  action  of  potassium  on  chloride  of  yttrium  is  very  intense. 
The  result,  after  separating  what  is  soluble  by  water,  is  a  metal  of  an 
iron  black  colour,  in  scaly  particles  of  a  perfectly  metallic  lustre  The 
fragments  appeared  to  be  brittle,  not  like  alumina,  ductile.  At  com- 
mon temperatures,  yttrium  is  not  combustible  in  air,  nor  oxidable  by 
water.  Heated  to  redness  it  burns  in  the  air,  and  its  combustion  in 
oxygen  is  one  of  the  most  brilliant  that  can  be  exhibited.  Its  remain- 
ing properties  closely  resemble  those  of  glucinum. 

YTTRIUM    AND    OXYGEN. 

Oxide  of  Yttrium  or  Yttria. — Atom.  Num.   402.    Symb. 
0+Y. 

Discovered  in  1794,  by  Professor  Gadolin,  in  a  very  rare  mineral 
from  Ytterby,  in  Sweden,  from  whence  it  derives  its  name,  and  sub- 
sequently examined  by  Klaproth  and  Vauquelin. 

PROPERTIES.  A  perfectly  white  and  very  ponderous  substance,  hav- 
ing a  specific  gravity  of  4*8  ;  devoid  of  taste  and  smell,  and  smooth  to 


ZIRCONIUM.  259 

the  touch;  insoluble  in  water,  and  infusible,  except  a  very  intense  heat; 
is  not  acted  upon  by  the  pure  alkalies,  by  which  it  is  distinguished  from 
alumina  and  glucina ;  but  is  slightly  soluble  in  carbonate  of  ammonia. 

REFERENCES.  For  the  process  for  obtaining  pure  Yttria,  see  Ann.  de  Chim. 
xxxvi.  150,  Also,  Henry,  Brande  and  Berzelius. 

SECTION  XL 
ZIRCONIUM. 

Atom.  Num.  30?  Symb.  Z. 

The  existence  of  the  metallic  basis  of  zirconia  was  rendered  proba- 
ble by  Sir  H.  Davy,  but  the  decomposition  of  this  earth  had  not  been 
effected  in  a  satisfactory  manner  till  the  year  1824,  when  Berzelius 
succeeded  in  obtaining  zirconium  in  an  insulated  state. 

PROPERTIES.  A  powder  as  black  as  charcoal,  which  may  be  boiled 
in  water  without  being  oxidized,  and  is  attacked  with  difficulty  by  sul- 
phuric, muriatic  or  nitromuriatic  acid,  but  is  dissolved  readily  and 
with  the  disengagement  of  hydrogen  gas,  by  hydrofluoric  acid  ;  when 
heated  in  the  open  air,  it  takes  fire  at  a  temperature  below  redness, 
burns  very  brightly,  and  is  converted  into  the  earth  ;  when  rubbed  be- 
tween two  hard  surfaces,  it  assumes  the  form  of  shining  scales,  of  a 
dark  gray  colour. 

PREPARATION.  The  process  for  obtaining  zirconium,  is  to  heat  a 
mixture  of  potassium  and  hydrofluate  of  zirconia  and  potassa,  careful- 
ly dried,  in  a  tube  of  glass,  or  iron,  by  means  of  a  spirit  lamp.  The 
reduction  takes  place  at  a  temperature  below  redness,  and  without 
emission  of  light.  The  mass  is  then  washed  with  boiling  water,  and 
afterwards  digested  for  some  time  in  dilute  muriatic  acid.  The  residue 
is  pure  zirconium. — Berzelius,  Traite  de  Chim.  ii.  382. 

ZIRCONIUM    AND    OXYGEN. 

Oxide  of  Zirconium — TArcnnia  or  Zircon. 

Discovered  in  1789  by  Klaproth,  in  the  Jargon  or  Zircon  of  Ceylon, 
and  since  found  in  the  hyacinth  and  in  the  cudialite  from  Greenland. 

PROPERTIES.  An  earthy  substance  resembling  alumina  in  appear- 
ance, of  specific  gravity  4-3,  having  neither  taste  nor  odour,  and  quite 
insoluble  in  water,  its  colour,  when  pure,  is  white,  but  it  has  frequent- 
ly a  tinge  of  yellow,  owing  to  the  presence  of  iron,  from  which  it  is 
separated  with  great  difficulty. 

The  composition  of  zirconia  has  not  yet  been  satisfactorily  deter- 
mined. From  some  analyses  of  Berzelius,  it  is  probable  that  the  atom- 
ic weight  of  this  earth  is  about  30  or  33. 

A  process  for  obtaining  pure  zirconia  is  described  by  MM  Duboi8 
and  Silveira. 

REFERENCES.  Webster's  Brande,  and  Henry's  Chem.  i.  661.  See  also, 
Berzelius,  Traite  de  Chim. ,  where  a  Sulphuret  and  a  Carburet  of  Zirconium 
are  described. 


260  SILICIUM. 

TESTS  OF  THE  SALTS.  The  salts  of  zirconia  are  distinguished  from 
those  of  alumina  and  glucina,  by  being  precipitated  by  all  the  pure 
alkalies,  in  an  excess  of  which  it  is  insoluble.  The  alkaline  carbonates 
precipitate  it  as  carbonate  of  zirconia,  and  a  small  portion  of  it  is  re- 
dissolved  by  an  excess  of  the  precipitant. 

SECTION  XII. 
SILICIUM. 

Atom.  Num.  7-5 — Symb.  Si. 

That  silica,  silex  or  silicious  earth,  is  composed  of  a  combustible  bo- 
dy combined  with  oxygen,  was  demonstrated  by  Sir  H.  Davy  ;  but 
pure  silicium  was  first  obtained  by  Berzelius  in  1824,  by  the  action  of 
potassium  on  fluosilisic  acid  gas. 

PROPERTIES.  Colour  dark  brown,  without  the  least  trace  of  metal- 
lic lustre  ;  a  non-conductor  of  electricity ;  incombustible  in  air  and 
in  oxygen  gas,  and  may  be  exposed  to  the  flame  of  the  blow -pipe 
without  fusing  or  undergoing  any  change  ;  soluble  in  a  mixture  of  ni- 
tric and  hydrofluoric  acids.  For  other  properties,  mode  of  preparation, 
&c.  see  Berzelius,  Traite  de  Chim.  i,  367. 

Some  uncertainty  still  prevails  with  regard  to  the  true  nature  of  sili- 
cium. As  it  wants  the  metallic  lustre  and  is  a  non  conductor  of  elec- 
tricity, it  cannot  perhaps  be  regarded  as  a  metal ;  and  hence  Berzelius, 
Thomson,  and  others,  place  it  with  carbon  and  boron,  among  the  non- 
metallic  combustibles.  Until  these  properties,  however,  are  more  com- 
pletely established,  it  may  be  proper  to  retain  it  in  the  present  class, 
more  especially  as  silica  is  so  nearly  allied  to  the  oxides  of  the  me- 
tals which  have  just  been  noticed. 

SILICIUM    AND    OXYGEN. 

Oxide  of  Silicium — Silica  or  Silex. — Atom.  Num.  15-5 — 
Symb.  O+Si. 

PROPERTIES.  When  artificially  prepared  it  is  a  perfectly  white  and 
tasteless  powder,  insipid,  inodorous,  and  feeling  harsh  between  the 
fingers  ;  insoluble  in  water,  and  not  acted  on  by  any  acid  except  the 
hydrofluoric  ;  it  is  fixed  in  the  fire,  and  is  very  infusible,  but  fuses  be- 
fore the  oxy-hydrogen  blow-pipe  with  greater  facility  than  lime  or 
magnesia ;  when  recently  prepared  and  very  minutely  divided,  it  is 
taken  up  by  the  fixed  alkalies,  and  henoe  by  some  chemists  termed 
Silicic  Acid,  and  its  compounds  with  alkaline  bases,  Silicates;  when 
mixed  with  carbonate  of  potassa,  and  exposed  to  strong  heat,  it  forms 
glass,  and  when  the  alkali  is  added  in  excess,  a  compound  is  obtained, 
formerly  termed  Liquor  Silicum  or  Liquor  of  Flints. 

It  is  insoluble  in  water. — This  is  true  when  silica  is  in  the  solid  form  ; 
but  Berzelius  has  shown  that,  when  silica  in  the  nascent  state  is  in 
contact  with  that  fluid,  it  is  dissolved  in  large  quantity.  On  evapo- 
rating the  solution  gently,  a  bulky  gelatinous  substance  separates, 
which  is  the  Hydrate  of  Silica.  This  hydrate  is  partially  decomposed 


SILICIUM.  261 

by  a  very  moderate  temperature ;  but  a  red  heat  is  required  for  ex- 
pelling the  whole  of  the  water.  According  to  Dr.  Thomson,  silica 
unites  with  water  in  several  proportions. — First  Prin.  i.  191. 

When  mixed  with  carbonate  of  potassa  and  subjected  to  heat,  it  forms 
glass. — It  is  owing  to  the  silicious  earth  which  it  contains,  that  glass 
is  decomposed  by  the  hydrofluoric  acid.  Glass,  however,  has  occa- 
sionally other  ingredients  besides  the  two  that  have  been  mentioned, 
the  object  of  which  admixtures  is  to  adapt  it  to  particular  purposes. 
Flint  glass  is  formed  of  fine  silicious  sand,  pearlash,  litharge  or  mini- 
um, a  little  nitre,  and  a  small  quantity  of  manganese  ;  Crown  glass, 
for  windows,  of  soda,  fine  silicious  sand,  lime,  and  fragments  of  glass  ; 
Green  bottle  glass,  of  sand,  kelp,  pearlash,  clay,  and  fragments  of  glass  ; 
and  Plate  glass,  of  fine  sand,  soda,  lime,  manganese,  oxide  of  cobalt, 
and  fragments  of  glass.  *  Pastes  or  artificial  gems,  are  only  another 
variety  of  glass,  into  the  composition  of  which,  borax  usually  enters, 
the  colours  being  given  by  various  metallic  oxides. — Henry,  i.  667. 

NATIVE  STATE  AND  PREPARATION.  Silica  exists  in  the  earth  in  great 
quantity.  It  enters  into  the  composition  of  most  of  the  earthy  min- 
erals ;  and  under  the  name  of  quartz  rock,  forms  independent  moun- 
tainous masses.  It  is  the  chief  ingredient  in  sandstones  ;  and  flint, 
calcedony,  rock  crystal,  and  other  analogous  substances,  consist  al- 
most entirely  of  silica,  t  Siliceous  earth  of  sufficient  purity  for  most 
purposes  may,  indeed,  be  procured  by  igniting  transparent  specimens 
of  rock  crystal,  throwing  them  while  red  hot  into  water,  and  then  re- 
ducing them  to  powder. — Brande. 

USES.  The  most  important  application  of  silex,  is  to  the  manufac- 
ture of  glass  ;  but  it  is  also  of  use  in  the  composition  of  porcelain  ; 
for,  absolutely  pure  clay,  without  an  admixture  of  silicious  earth, 
would  shrink  too  much  to  be  fit  for  the  uses  of  the  potter.  When 
mixed  with  slaked  lime  it  forms  mortar,  which  is  used  as  a  cement  for 
building.  According  to  Dr.  Higgins  the  best  proportions  are  three 
parts  of  fine  sand,  four  parts  of  coarser  sand,  one  part  of  quicklime 
recently  slaked,  and  as  little  water  as  possible.  The  stony  hardness 
which  mortar  acquires  has  been  ascribed  to  the  absorption  of  carbonic 
acid,  and  to  a  combination  of  part  of  the  water  with  the  lime.  But  I 
concur  in  the  suggestion  of  Mr.  Donovan  that  it  is  rather  to  be  as- 
cribed to  a  sort  of  chemical  union  of  the  silica  and  lime ;  a  theory 
which  accounts  for  the  hardness  of  mortar  in  the  interior  of  thick  old 
walls,  where  carbonic  acid  could  scarcely  have  penetrated,  and  which 
scarcely  effervesces  when  treated  with  "acids.  [On  this  subject  see 
Thomson  Inorg.  Chem.  i.  440,  and  Donovan  Chemistry.  257.  ] 

REFERENCES.  Faraday's  process  for  obtaining  Silica,  Chem.  Manip. — 
For  a  good  account  of  the  different  varieties  of  Glass,  see  Aikitfs  Diet,  of 
Chem.  art.  Glass.  Also,  Guyton  Morv'eau,  in  Ann.  de  Chirn.  Ixxii.  or  Re- 
pert,  of  Arts,  2d  ser.  xix.  307,  068. 

*  It  is  of  some  importance  to  the  analyst  to  be  a\yare  that  glass  to  a  cer- 
tain extent  is  decomposable  by  water.  If  son\e  of  it  in  a  powdered  state  be 
triturated  with  distilled  water,  in  a  short  time  the  turmeric  test  will  indicate  a 
portion  of  alkali  in  solution. 

f  Corn  and  grasses  contain  silex  and  sufficient  potash  to  form  glass.  A 
very  pretty  experiment  may  be  made  on  these  plants  with  a  blowpipe.  If 
you  take  a  straw  of  wheat,  barley,  or  hay,  and  burn  it,  beginning  at  the  top 
and  heating  the  ashes  with  the  blue  flame,  you  will  obtain  a  perfect  globule 
of  hard  glass  fit  for  microscopic  experiments. — Davy. 


262  SILICIUM. 

Chloride  of  Silicium. — When  silicium  is  heated  in  a  current  of  chlo- 
rine gas,  it  takes  fire  and  is  rapidly  volatilized.  The  product  of  the 
combustion  condenses  into  a  liquid,  which  appears  to  be  naturally 
colourless,  but  to  which  an  excess  of  chlorine  communicates  a  yellow 
tint.  This  fluid  is  very  limpid  and  volatile,  and  evaporates  almost  in- 
stantaneously in  open  vessels  in  the  form  of  a  white  vapour.  It  has  a 
suffocating  odour  not  unlike  that  of  cyanogen,  and  when  put  into 
water  is  converted  into  muriatic  acid  and  silica,  the  latter  being  easily 
obtained  in  the  gelatinous  form. — Berzelius,  Traite  de  Chim.  i.  374. 

Bromide  of  Silicium. — This  compound  may  be  obtained  in  the  same 
way  as  that  just  described,  merely  substituting  the  vapour  of  bromine 
for  chlorine.  When  purified  from  free  bromine  by  mercury,  and  re- 
distilled, it  is  a  colourless  liquid,  which  emits  dense  vapours  in  an  open 
vessel,  being  decomposed  by  the  moisture  of  the  air,  arid  is  denser  than 
strong  sulphuric  acid.  At  302D  F.  it  enters  into  ebullition,  and  freezes 
at  10J.  Potassium  when  gently  heated,  acts  on  it  with  so  much  en- 
ergy that  detonation  ensues.  By  water  it  is  resolved  into  hydrobro- 
rnic  acid  and  silica. — Phil.  Mag.  and  Ann.  xi.  395. 

Fluosilicic  Acid.— Atom.  Num.  26-18—  Symb.  F+S. 

SYN.     Silicated  Fluoric  Acid.     Fluoride  of  Silicium. 

PROPERTIES.  A  colourless  gas,  which  extinguishes  flame,  destroys 
animals  that  are  immersed  in  it,  and  irritates  the  respiratory  oigans 
powerfully  ;  it  does  not  corrode  glass  vessels  provided  they  are  quite 
dry  ;  when  mixed  with  atmospheric  air  it  forms  a  white  cloud,  owing 
to  the  presence  of  watery  vapour  ;  specific  gravity  according  to  Thom- 
son, 3-61  ;  is  powerfully  acted  on  by  water,  which  dissolves  about  365 
times  its  volume,  [Davy,  Phil.  Trans.  1812]  and  during  absorption  de- 
positing silica. 

PREPARATION-.  This  gas  is  formed  whenever  hydrofluoric  acid 
comes  in  contact  with  silicious  earth  ;  and  this  is  the  reason  why  pure 
hydrofluoric  acid  can  be  prepared  in  metallic  vessels  only,  and  with 
fluor  spar  that  is  free  from  rock  crystal.  The  most  convenient  me- 
thod of  procuring  the  gas  is  to  mix  in  a  retort  one  part  of  pulverized 
fluor  spar  with  its  own  weight  of  sand  or  pounded  glass,  and  two  parts 
of  strong  sulphuric  acid.  On  applying  a  gentle  heat,  fluosilicic  acid 
gas  is  disengaged  with  effervescence,  and  may  be  collected  over  mer- 
cury. 

This  compound  is  probably  a  fluoride  of  silicium  and  does  not  pos- 
sess acid  properties  ;  but  when  dissolved  in  water  it  is  converted  into 
Silico-hydrojliwric  Acid,  by  the  decomposition  of  the  water,  the  hydro- 
gen combining  with  the  fluorine,  the  oxygen  with  the  silicium. 

The  Silico -hydrofluoric  Add,  or  as  it  is  also  called  Silicaf.ed  Flu- 
oric Acid,  unites  with  bases  and  forms  compounds  which  have  been  in- 
vestigated by  Berzelius.— Jinn,  of  Phil.  xxiv.  450. 

Sulphvret  of  Silicium  —  a  white  earthy  looking  substance,  formed 
by  healing  silicium  in  the  vapour  of  sulphur.  By  the  action  of  wa- 
ter it  is  instantly  converted  into  sulphuretted  hydrogen  and  silica, 
the  former  escaping  with  effervesence,  the  latter  dissolved  in  large 
quantity. 

Carburet,  of  Silicium — When  silicium  is  reduced  by  means  of  po- 
tassium, prepared  by  heating  to  redness  carbonate  of  potassa  with 
charcoal  and  afterwards  purifying  it  by  fusion,  there  results  a  mixture 


THORIUM.  263 

of  silicium  and  carburet  of  silicium.  This  compound  is  of  a  darker 
colour  than  the  pure  silicium  and  by  combustion  affords  carbonic  acid. 
—  Berzelius,  Traite  de  Chim.  i.  375. 

SECTION  XIII. 
THORIUM. 

Atom.  Num.  59  6  ?—Sym1>.  Th. 

The  metallic  basis  of  thorina,  a  new  earth  discovered  by  Berzelius, 
in  1829. 

PROPERTIES.  A  gray  metallic  powder,  incapable  of  decomposing1 
water,  but  which  when  heated  above  redness,  burns  with  a  splendour 
nearly  equal  to  that  of  the  combustion  of  phosphorus  in  oxygen  ;  it 
is  but  slightly  acted  upon  by  nitric  or  sulphuric  acid,  but  muriatic  acid 
dissolves  it  with  brisk  effervesence. 

This  metal  is  obtained  by  decomposing  chloride  of  thorinum  by  means 
of  potassium. — Berzelius,  Traite  de  Chim.  ii.  391. 

THORIUM    AND    OXYGEN. 

Oxide  of  Thorium  or  Thoria.—Jltom.  Num.  67-6  ? — Symb. 
O+Th. 

A  constituent  of  a  new  mineral  found  in  Brevig,  in  Norway,  to 
which  Berzelius  has  given  the  name  formerly  applied  to  a  substance 
erroneously  supposed  by  him  to  be  an  earth,  but  which  he  afterwards 
ascertained  to  be  a  phosphate  of  yttria. 

PROPERTIES.  Thoria  is  white  and  irreducible  by  charcoal  and  po- 
tassium ;  specific  gravity  9-4  ;  when  strongly  ignited  is  not  attacked 
by  any  of  the  acids  except  the  concentrated  sulphuric  ;  dissolves  read- 
ily in  carbonate  of  ammonia,  and  on  heating  the  solution  a  portion  of 
the  earth  is  precipitated,  but  is  afterwards  re-dissolved  as  the  solution 
cools. — Berzelius. 


264  MANGANESE. 


CLASS  IV. 

METALS  WHICH  DECOMPOSE  WATER  ONLY  WHEN  THEY  ARE 
HEATED  TO  REDNESS. 


* 

SECTION  XIV. 
MANGANESE. 

Atom.  Num.  27*7 — Symb.    Mn. — Sp.   gr.  6*85.  Bergman. 
8-013  John. 

Although  this  substance  has  been  long  known,  its  nature  was  not 
understood.  By  the  older  chemists  it  was  generally  considered  as  an 
ore  of  iron.  It  was  proved  to  be  a  distinct  metal  by  Scheele  and  Gahn 
in  1774. — Scheele' s  Chem.  Essays. 

PROPERTIES.  A  hard  brittle  metal,  of  a  grayish  white  colour  and 
granular  texture  ;  when  pure  is  not  attracted  by  the  magnet ;  is  ex- 
ceedingly infusible,  requiring  a  heat  of  160°  Wedgewood  for  fusion  ; 
soon  tarnishes  on  exposure  to  the  air,  and  absorbs  oxygen  with  rapidity 
when  heated  to  redness  in  open  vessels  ;  it  is  said  to  decompose  water 
at  common  temperature,  with  disengagement  of  hydrogen  gas,  though 
the  process  is  exceedingly  slow,  but  at  a  red  heat  decomposition  is  ra- 
pid, and  protoxide  of  manganese  is  the  result. 

EXTRACTION.  Manganese,  owing  doubtless  to  its  powerful  affinity  for 
oxygen,  has  never  been  found  in  an  uncombined  state  in  the  earth  ; 
but  the  peroxide  of  manganese  occurs  abundantly.  This  metal  re- 
tains its  oxygen  with  such  force  that  its  oxides  require  a  stronger  heat 
for  reduction  than  potassa  or  soda.  The  method  by  which  Ghan  suc- 
ceeded in  procuring  metallic  manganese,  was  by  exposing  the  perox- 
ide, surrounded  with  charcoal,  to  the  most  intense  heat  of  a  smith's 
forge  ;  and  this  process  has  been  successfully  repeated  by  others. — 
[Berthier,  in  Ann.  de  Chim.  et  de  Phys.  xx. — Turner.]  Dr.  Thomson  re- 
capitulates several  processes  for  obtaining  metallic  manganese. — Inorg. 
Chem.  i.  512. 

MANGANESE    AND    OXYGEN. 

Much  labour  has  been  employed  by  chemists  in  the  investigation  of 
the  oxides  of  manganese,  a  subject  of  greater  difficulty  than  might 
have  been  supposed.  Those  who  have  contributed  most  to  our  know- 
ledge concerning  them,  are  John,  Berzelius,  Forchhammer,  Berthier, 
Arfwedson,  Thomson  and  Turner. 


MANGANESE.  265 

The  following  are  now  recognized  as  distinct  compounds  of  oxygen 
and  manganese  : 

O.  Mn. 

Protoxide,  8+27-7  or   O-f  Mn.=  35-7 

Sesqui-oxide,  12+27-7       30+2Mn.=  79-4 

Peroxide,  16+27-7       20+  Mn.=  43-7 

Red  Oxide,  10-66+27-7       40+3Mn.=115-l 

Varvicite,  14+27-7       70+4Mn.=166-8 

Manganeseous  acid,  24+27 -7        30+  Mn.=  51-7 
Manganesic  acid,      28+27-7       70+2Mn.=lll-4 

Protoxide   of  Manganese. — Atom.   Num.   35'7 — Symb. 
O+Mn. 

PROPERTIES.  When  pure,  of  a  mountain  green  colour  ;  according  to 
Turner  undergoing  no  change  by  exposure  to  air  for  nineteen  days  ; 
at  600°  F.  is  oxidized  with  considerable  rapidity,  and  at  a  low  red  heat 
is  converted  in  an  instant  into  the  red  oxide  ;  unites  readily  with  acids 
and  forms  colourless  salts. 

PREPARATION.  This  oxide  may  be  formed  as  was  shown  by  Ber- 
thier,  by  exposing  peroxide,  sesquioxide  or  red  oxide  of  manganese  to 
the  combined  agency  of  charcoal  and  a  white  heat ;  or  by  exposing 
either  of  the  oxides  of  manganese  contained  in  a  tube  of  glass,  porce- 
lain, or  iron,  to  a  current  of  hydrogen  gas  at  an  elevated  temperature, 
as  described  by  Dr.  Forchhammer. — Ann.  of  Phil.  xvii.  52. 

Sesquioxide  of  Manganese. — Atom.  Num.   79*4 — 8ymb. 
30+2  Mn. 

PROPERTIES.  Colour  brownish  or  nearly  black,  depending  upon  the 
source  from  whence  it  is  obtained  ;  it  is  acted  upon  by  sulphuric  and 
nitric  acids  ;  when  exposed  to  the  air  absorbs  oxygen  and  is  converted 
into  the  peroxide. 

NATIVE  STATE  AND  PREPARATION.  This  oxide  occurs  nearly  pure 
in  nature,  and  as  a  hydrate  it  is  found  abundantly,  often  in  large  pris- 
matic crystals,  at  Ihlefeld  in  the  Hartz.  It  may  be  formed  artificially 
by  exposing  peroxide  of  manganese  for  sometime  to  a  moderate  red 
heat,  and  is  therefore  the  chief  residue  of  the  usual  process  for  obtain- 
ing oxygen  gas  ;  but  it  is  difficult  so  to  regulate  the  degree  of  the  dura- 
tion of  the  heat,  that  the  resulting  oxide  shall  be  quite  pure. 

Peroxide  of  Manganese. — Atom.  Num.  43"7— •Symk 
.   20+Mn. 

A  very  abundant  ore,  commonly  called  Black  Oxide  of  Manganese, 
the  nature  of  which  was  demonstrated  by  Scheele,  in  1774. 

PROPERTIES.  Occurs  massive,  of  an  earthy  appearance,  mixed  with 
various  other  substance,  or  in  the  form  of  minute  prisms  ;  it  is  un- 
changed by  exposure  to  the  air  ;  is  insoluble  in  water  ;  does  not  unite 
with  acids  or  alkalies  ;  yields  oxygen  gas  when  heated  to  redness,  or 


266  MANGANESE. 

when  boiled  with  sulphuric  acid,  in  the  former  case  it  is  converted  into 
the  sesquioxide,   in  the  latter  a  sulphate  of  the  protoxide  is  formed. 

USBIS.  This  oxide  is  employed  in  the  arts  for  discolouring  glass,  and 
in  preparing  chlorine  for  hleaching.  In  the  laboratory  it  is  used  for 
procuring  chlorine  and  oxygen  gases,  and  in  the  preparation  of  the 
saj|s  of  manganese. 

Red^  Oxide  of  Mangnnese  and  Oxidum  manganoso-manganicum  of 
Arfwedson.  These  Dr.  Turner  has  shown  to  be  identical.  The  oxide 
of  ^-fwedson  occurs  as  a  natural  product,  the  other  may  be  formed 
artificially  by  exposing  the  peroxide  or  sesquioxide  to  a  white  heat, 
either  in  close  or  in  open  vessels.  Its  colour  is  variable,  but  when 
rubbed  to  the  same  degree  of  fineness,  it  is  always  of  a  brownish  red 
colour  when  cold,  and  nearly  black,  while  warm.  It  does  not  change 
its  state  of  oxidation  by  being  ignited  in  contact  with  air.  It  dis- 
solves in  muriatic  acid,  with  a  disengagement  of  chlorine,  and  com- 
municates a  deep  red  colour  to  the  acid,  which  disappears  on  keep- 
ing. 

The  red  oxide  contains  more  oxygen  than  the  protoxide,  and  less 
than  the  deutoxide.  Its  elements  are  in  such  proportion  that  it  may 
be  regarded  as  a  compound,  either  of  two  proportions  of  protoxide  and 
one  proportion  of  peroxide,  or  two  proportions  sesquioxide  and  one  pro- 
toxide.— Turner. 

Varvicite. — A  compound  known  only  as  a  natural  production,  having 
been  first  noticed  a  few  years  since  by  Mr.  Phillips  among  some  ores 
of  manganese  found  in  Warwickshire.  In  the  colour  of  its  powder  and 
in  its  hardness  it  bears  considerable  resemblance  to  the  peroxide  of 
manganese  for  which  it  was  at  first  mistaken.  But  it  is  readily  dis- 
tinguished from  that  ore  by  its  stronger  lustre  ;  it  highly  lamellated 
texture  which  is  very  similar  to  that  of  manganite.  and  by  its  yielding 
water  freely  when  heated  to  redness.  Its  specific  gravity  is  4-531. — 
When  strongly  heated  it  is  converted  into  red  oxide,  losing  5*725  per 
cent,  of  water,  and  7'385  of  oxygen.  It  is  probably,  like  the  red  oxide, 
a  compound  of  two  other  oxides;  and  the  proportions  just  slat- 
ed justify  the  supposition  that  it  consists  of  one  atom  of  peroxide,  and 
one  of  sesquioxide  of  manganese,  united  in  the  mineral  with  half  an 
atom  of  water. — Turner — Phil.  Mag.  and  Ann.  v.  209.  vi.  281,  and  vii. 
284. 

REFERENCES.  Dr.  Joints  Contributions  towards  a  chemical  knowledge  of 
Manganese,  Ann.  of  Phil,  ii.  172.  Serzelius,  Traite  de  Chin.  iii.  1296.  Gay 
Lvssac,  Ann.  de  Chim.  et  de  Phys.  i.  39.  Thenard,  Traite  de  Chim.  ii.  341 
Arfwedson,  Arm.  of  Phil,  xxiii.  267.  Berthier,  Ann.  de  Ch.  et  de  Phys.  xv 
Thomson's  First  Prin.  i.  364.  Turner,  in  Phil.  Trans.  ofEdin.for  1828' 
or  Phil.  Mag.  and  Ann.  iv.  22, 96. 

Manganeseous  and  Mangancsic  Acids. 

When  the  peroxide  of  manganese  is  mixed  with  an  equal  weight  of 
nitre  or  carbonate  of  potassa,  and  the  mixture  exposed  to  a  red  heat,  a 
green  coloured  fused  mass  is  obtained,  which  has  long  been  known  by 
the  name  of  Mineral  Chamelion.  On  dissolving  this  substance  in  wa- 
ter, a  green  solution  is  obtained  ;  the  colour  of  which  soon  changes  in 
succession  to  blue,  purple  and  red,  and  ultimately  disappears  entirely. 
The  experiment  may  be  varied  by  putting  equal  quantities  of  this  sub- 
stance into  two  glass  vessels,  arid  pouring  in  the  one  hot,  and  into  the 


MANGANESE.  267 

other  cold  water.  The  hot  solution  will  have  a  beautiful  green  colour, 
and  the  cold  a  deep  purple.  The  shades  will  vary  as  the  temperature 
alters. 

From  the  researches  of  Dr.  Forchhammer  it  is  probable  that  the 
green  and  red  colours  are  produced  by  two  distinct  acids,  the  Manga- 
neseous  and  Manganesic  ;  one  of  which  forms  red  and  the  other  green 
coloured  salts  ;  and  very  recently  Mitscherlich  has  established  the  ex- 
istence of  these  acids  and  ascertained  their  composition.  He  proposes 
to  distinguish  them  by  the  names  of  Manganic  and  permanganic  acids, 
from  the  circumstance  of  his  finding  the  green  coloured  salts  isomor- 
phous  with  the  sulphates  ;  and  the  red  salts  isomorphous  with  the  per- 
chlorates.  —  Jinn,  de  Ckim.  et  de  Phys.  xlix.  113.  Ann.  of  Phil.  xvi.  130. 
Henri/  s  Chem.  ii-  12.  Sec  also  Berzelius,  Traite  de  Chim.  iii.  296,  and 
Unverdorben,  in  Phil.  Mag.  and  Ann.  ii.  393. 

MANGANESE    AND    CHLORINE. 

Chemists  are  acquainted  with  two  compounds  of  chlorine  and  man- 
ganese. 

Proto  chloride  of  Manganese.  —  Jltom.Num.  63*15  —  Symb. 
Cl+Mn. 

PROPERTIES.  A  pink  coloured  semi-transparent  substance  ;  deli- 
quescent, and,  of  course,  very  soluble  in  water,  being  converted  by 
that  fluid,  with  the  evolution  of  caloric,  into  Muriate  of  Manganese. 

PREPARATION.  This  chloride  is  best  prepared  by  evaporating  a  solu- 
tion of  muriate  of  manganese  to  dryness,  by  gentle  heat,  and  heating 
the  residue  to  redness  in  a  glass  tube,  while  a  current  of  muriatic  acid 
as  is  transmitted  through  it.  The  heat  of  a  spirit  lamp  is  sufficient 
or  the  purpose. 


g 
fo 


Perchloride  of  Manganese.  —  Atom.  Num.  303-55  —  Symb.} 
7C1+2  MM. 


A  new  compound  discovered  by  Dumas. 

PROPERTIES.  A  volatile  compound,  appearing  when  first  formed,  as 
a  vapour,  of  a  copper  or  greenish  colour  ;  but  on  traversing  a  glass 
tube,  cooled  to  5°  or  -4D  F.  is  condensed  into  a  greenish-brown  colour- 
ed liquid  ;  when  the  air  of  a  large  tube  is  displaced  by  the  gas,  and 
this  is  poured  into  a  larger  tube,  the  interior  of  the  latter  being  first 
moistened  with  water,  a  dense  rose-coloured  fume  appears,  and  the 
inside  of  the  vessel  acquires  a  deep  purple  colour  ;  a  circumstance 
caused  by  the  instantaneous  production  of  muriatic  and  manganesic 
acids. 

PREPARATION.  This  chloride  is  easily  prepared  by  putting  a  solution 
of  manganese  into  strong  sulphuric  acid,  and  then  adding  fused  sea 
salt.  The  muriatic  and  manganesic  acids  mutually  decompose  each 
other  ;  water  and  perchloride  of  manganese  are  generated,  and  the 
latter  escapes  in  the  form  of  vapour. 

REFERENCES.  Dumas ,  in  Ann.  de  Chim.  et  de  Phys.  xxxvi.  81,  or  Edin. 
Jour,  of  Science,  viii.  179. 


268  MANGANESE. 


MANGANESE    AND    FLUORINE. 

Fluoride  of  Manganese. — Atom.  Num.  186-16 — Symb.  7 
F+2  Mn. 

Discovered  by  Dumas  and  Wohler,  and  described  in  Ann.  de  Chim.  et 
de  P/tys.  Jan.  1828. 

PROPERTIES.  A  gaseous  compound  or  vapour,  of  a  yellowish-green 
colour  ;  when  mixed  with  atmospheric  air,  it  acquires  instantly  a 
beautiful  purple  red  colour  ;  is  freely  absorbed  by  water,  yielding  a  so- 
lution of  the  same  red  tint ;  it  acts  instantly  on  glass,  with  the  for- 
mation of  fluosilicic  acid  gas,  a  brown  matter  being  at  the  same  time 
deposited,  which  becomes  of  a  deep  purple  red  tint,  on  the  addition  of 
water. 

PREPARATION.  This  compound  may  be  prepared  by  mixing  common 
mineral  chamelion  with  half  its  weight  of  fluor  spar  and  decomposing 
the  mixture  in  a  platinum  vessel  by  fuming  sulphuric  acid. 

Sulphuret  of  Manganese. — This  compound  may  be  procured  by  ig- 
niting the  sulphate  with  one-sixth  of  its  weight  of  charcoal  in  powder. 
[Berthier.]  It  is  also  formed  by  the  action  of  sulphuretted  hydrogen 
on  the  protosulphate  at  a  red  heat.  [  Arfwedson.  ]  It  occurs  native  in 
Cornwall  and  at  Nagyag,  in  Transylvania.  It  dissolves  completely  in 
dilute  sulphuric  or  muriatic  acid,  with  disengagement  of  very  pure 
sulphuretted  hydrogen  gas. — Turner. 

Phosphuret  and  Carburet  of  Manganese,  may  be  obtained  by  heat- 
ing the  metal  in  contact  with  phosphorus  or  carbon. — Berzelius,  Traite 
de  Chim.  iii.  309. 

MANGANESE    AND    THE    METALS. 

According  to  Berzelius  manganese  combines  with  silicium,  gold, 
silver,  copper  and  iron.  The  alloy  of  manganese  and  iron  is  whiter 
than  iron,  hard  and  brittle,  and  it  is  said  to  be  most  proper  for  the  fabri- 
cation of  steel. 

SALTS    OF    MANGANESE. 

Nitrate   of  Manganese. — Atom.  Num.  152-7 — Symb. 
(50+N)+(0+MnO+7  Aq. 

PROPERTIES.  A  salt  with  difficulty  obtained  in  crystals  ;  colour 
similar  to  that  of  the  carbonate  ;  it  deliquiates  rapidly  when  exposed  to 
the  air,  and  on  the  application  of  heat  melts,  and  is  immediately  de- 
composed. 

PREPARATION.  This  salt  may  be  obtained  by  the  action  of  dilute 
nitric  acid  upon  protoxide  of  manganese,  or  by  digesting  peroxide  of 
manganese  in  nitric  acid,  with  some  gum  or  sugar,  which  abstracts 
oxygen,  carbonic  acid  is  evolved,  and  the  protoxide  dissolved  by  the 
acid. 


MANGANESE.  269 

Sulphate  of  Manganese.—  Atom.  Num.  120.7—  Symb. 
(30+S)+(0+Mn.)+5  Aq. 

PROPERTIES.  A  rose  coloured  salt,  of  a  bitter  styptic  taste,  very 
soluble  in  water  ;  crystallizing  in  very  flat  rhombic  prisms  :  at  a  bright 
red  heat  it  gives  out  oxygen,  and  sulphurous  acid  and  sesquioxide  of 
manganese  remain. 

This  salt  is  prepared  by  dissolving  pure  carbonate  of  manganese  in 
moderately  dilute  sulphuric  acid,  and  setting  the  solution  aside  to 
crystallize  spontaneously. 

With  sulphate  of  ammonia,  this  salt  yields  a  double  sulphate  of  am- 
monia and  manganese,  consisting  of  one  proportion  combined  with 
eight  of  water.  It  is  isomorphous  with  the  analogous  salts  of  mag- 
nesia and  protoxide  of  iron.  —  Turner. 

Phosphate  of  Manganese.  —  Atom.  Num.  89.4  —  Symb. 

Aq. 


PROPERTIES.  A  tasteless  white  powder,  insoluble  in  water,  and  pro- 
ducing no  alteration  on  vegetable  blues  ;  when  heated  to  redness  gives 
out  water,  and  leaves  anhydrous  phosphate. 

This  salt  is  obtained  by  mixing  together  solutions  of  sulphate  of 
manganese  and  phosphate  of  soda.  The  phosphate  of  manganese 
precipitates  in  the  state  of  a  white  powder,  which  may  be  collected  on 
a  filter,  washed  and  dried  in  the  open  air. 

Carbonate  of  Manganese.  —  Atom.  Nam.  75'7  —  Symb. 
(20+C)+(0+Mn.)+2  Aq. 

PROPERTIES.  A  snow  white  tasteless  powder,  insoluble  in  water, 
and  when  kept  for  some  time  is  converted  into  black  oxide  of  manga- 
nese. 

This  salt  is  prepared  by  adding  a  carbonated  alkali  to  a  salt  with  a 
base  of  protoxide  of  manganese.  Dr.  Turner  thinks  it  probable  that 
it  is  strictly  anhydrous. 

TESTS  OF  THE  SALTS  OF  MANGANESE.  The  salts  of  manganese  con- 
taining the  protoxide,  are  mostly  soluble  in  water,  and  the  solution 
becomes  turbid  and  brown  by  exposure  to  air.  They  are  not  preci- 
pitated by  hydriodic  acid  ;  they  furnish  white  precipitates  with  the 
alkalies,  which  soon  become  discoloured  by  exposure  to  air  ;  they  are 
precipitated  white  by  ferro-cyanate  of  potassa,  and  yellow  by  hydro- 
sulphuret  of  ammonia. 


270  IRON. 

SECTION  XV. 
IRON. 

Atom.  Num.   28.—  Symb.  Fe.«— %  gr.  7-78. 

Iron  has  been  known  from  the  most  remote  periods,  and  is  the  most 
diffused,  the  most  abundant,  and  the  most  important  of  the  metals.  It 
was  formerly  called  Mars,  and  hence  the  term  Martial  was  applied  to 
its  compounds. 

PROPERTIES.  This  metal  has  a  bluish- white  colour ;  it  is  suscepti- 
ble of  a  high  polish  ;  it  is  very  malleable,  and  is  capable  of  being 
drawn  into  very  fine  wire,  though  not  of  being  beaten  into  very  thin 
leaves  ;  in  its  pure  state  is  exceedingly  infusible,  but  this  disadvantage  is 
counterbalanced  for  all  practical  purposes,  by  its  possessing  the  proper- 
ty of  iceldmg  in  high  perfection  ;  its  hardness  exceeds  that  of  most  of 
the  metals,  and  it  may  be  rendered  harder  than  most  bodies  when  con- 
verted into  steel ;  it  is  attracted  by  the  magnet  and  may  itself  have  the 
magnetic  virtue  imparted  to  it. 

Iron  is  malleable  and  ductile. —  This  metal  is  malleable  in  every  tem- 
perature, and  its  malleability  increases  in  proportion  as  the  tempera- 
ture augments  ;  but  it  cannot  be  hammered  out  nearly  so  thin  as  gold 
or  silver,  or  even  copper.  Its  ductility,  however,  is  more  perfect,  for 
it  can  be  drawn  out  into  wire  as  fine,  at  least,  as  a  human  hair. 

It  is  acted  on  by  the  Magnet. — Iron  is  attracted  by  the  magnet,  and  it 
is  upon  this  principle  that  iron  filings  are  often  freed  from  sand  and  oth- 
er impurities.  [See  page  85}  When  perfectly  pure,  iron  retains  the 
magnetic  virtue  for  a  short  time  only,  but  when  combined  with  car- 
bon so  as  to  form  steel  it  may  be  rendered  permanently  magnetic. 

NATIVE  STATE  AND  EXTRACTION.  Iron  is  rarely  found  native  in  its 
pure  state ;  the  meteoric  iron  being  alloyed  with  nickel  and  cobalU 
It  is  artificially  procured  by  heating  the  native  oxide  with  charcoal : 
but  when  thus  obtained,  it  is  never  quite  free  from  carbonaceous  mat- 
ter. The  only  method  of  preparing  iron  absolutely  pure,  is  by  pass- 
ing dry  hydrogen  gas  over  the  pure  oxide,  heated  to  redness  in  a  tube 
of  porcelain. 

REFERENCES.  A  notice  of  a  mass  of  pure  native  Iron,  found  m  Connecti, 
cut  by  Mr.  Burrall,  see  SiUimarfsJour.  xii.  154.  For  a  table  of  the  principal 
Meteoric  Stones  which  have  fallen  from  1735  to  1815,  see  Thenard,  i.  369; 
also  Cteaveland's  Mineralogy.  For  an  account  of  the  various  processes  for 
extracting  Iron  from  its  Ore?,  see  Aikirfs  or  Ure^s  Chemical  Dictionary.. 

IRON    AND    OXYGEN. 

Iron  combines  with  oxygen  in  two  proportions  only,  forming  the 
blue  or  protoxide,  and  the  red  or  peroxide.  Both  these  compounds 
are  capable  of  yielding  regular  crystalline  salts  with  acids. 

*  From  the  latin  word  Ferrum* 


IRON.  271 


Protoxide  of  Iron. — Atom.  Num.  36 — Symb.  O-j-Fe. 

Although  the  existence  of  this  compound  was  inferred  some  years 
since  by  Gay  Lussac,  it  was  first  obtained  in  an  insulated  form  by 
Stromeyer. 

PROPERTIES.  A  compound  of  a  dark  blue  colour,  which  when  melt- 
ed with  vitreous  substances,  communicates  to  them  a  tint  of  blue  ; 
it  is  attracted  by  the  magnet,  though  less  powerfully  than  metallic 
iron  ;  it  is  exceedingly  combustible,  for  when  fully  exposed  to  air  at 
common  temperatures,  it  suddenly  takes  fire,  and  burns  vividly,  being 
reconverted  into  the  peroxide  ;  all  its  salts,  particularly  when  in  so- 
lution, absorb  oxygen  with  such  rapidity,  that  they  may  even  be  em- 
ployed in  eudiometry. 

NATIVE  STATE  AND  PREPARATION.  This  oxide  is  the  base  of  the  na- 
tive carbonate  of  iron,  and  of  the  green  vitriol  of  commerce.  It  may 
be  obtained  in  an  insulated  form,  by  transmitting  dry  hydrogen  gas 
over  the  peroxide  of  iron,  at  a  very  low  temperature. 

REFERENCES.  Gay  Lussac,  Ann.  de  Chim.  Ixxx.  163;  Stromeyer,  Edin 
Jour,  of  Science,  v.  300. 

Peroxide  of  Iron. — Atom.  Num.  40 — Symb.  IJO+Fe. 

SYN.     Crocus  Martis — Saffron  of  Mars. 

PROPERTIES.  This  oxide  is  of  a  brownish  red  colour,  and  is  not  at- 
tracted by  the  magnet ;  it  forms  salts  generally  of  a  red  colour,  the 
solutions  of  which  are  precipitated  of  a  fine  blue  by  ferro-cyanate  of 
potassa,  and  of  an  intense  bluish  black,  by  infusion  of  galls. 

NATIVE  STATE  AND  PREPARATION.  This  oxide  is  an  abundant  natur- 
al product,  known  by  the  name  of  Red  Hematite,  occurring  massive 
or  crystallized.  It  may  be  artificially  prepared  by  adding  an  alkali 
to  a  solution  of  iron  in  nitromuriatic  acid  ;  a  brownish  red  hydrate 
subsides,  which  is  identical  in  composition  with  the  mineral  called 
Broion  Hematite,  and  consists  of  one  proportion  of  peroxide,  and  one 
of  water. 

Black  Oxide  of  Iron. — This  substance,  long  supposed  to  be  the  pro- 
toxide of  iron,  contains  more  oxygen  than  the  blue,  and  less  than  the 
red.  It  is  most  probably,  not  a  definite  compound  of  iron  and  oxy- 
gen, but  is  composed  of  the  two  real  oxides,  united  in  a  proportion  which 
is  by  no  means  constant.  [Twr/ier.j  It  occurs  native,  frequently 
crystallized  in  the  form  of  a  regular  octahedron,  which  is  not  only  at- 
tracted by  the  magnet,  but  is  itself  sometimes  magnetic,  and  is  then 
known  under  the  name  of  Magnetic  Iron  Ore,  which  is  abundant  in  va- 
rious parts  of  o:ir  country.  Another  variety  of  this  oxide  is  called 
Iron  Glance  and  Micaceous  Iron  Ore.  It  is  from  these  ores  that  iron  is 
generally  obtained. 

This  oxide  is  always  formed  when  iron  is  heated  to  redness  in  the 
open  air  ;  and  is  likewise  generated  by  the  contact  of  aqueous  va- 
pour with  iron,  at  elevated  temperatures.  But  the  composition  of  the 
product  varies  with  the  duration  of  the  process  and  the  temperature 
employed. 


272  IRON. 

REFERENCES.  On  the  Oxides  of  Iron,  see  Berzelius,  Trails  de  Chim.  iii 
249;  Thenard,  ii.  348;  Thomson's  First  Prin.  i.  343;  Mosander,  Edin. 
Jour,  of  Science,  iv.  137. 

IRON    AND    CHLORINE. 

Iron  and  chlorine  combine  in  two  proportions,  forming  compounds 
first  described  by  Dr.  John  Davy.— PM.  Trans,  for  1812. 

Protochloride  of  Iron— Atom.  Num.  63-45—  Symb.  Cl+Fe. 

A  compound  of  a  gray  colour,  metallic  splendour,  and  lamellated 
texture,  requiring  a  red  heat  for  its  fusion,  and  converted  by  water  in- 
to the  Protomuriate  of  Iron.  It  is  formed  by  dissolving  iron  in  dilute 
muriatic  acid,  evaporating  the  solution  to  dryness,  and  igniting  the 
precipitate  out  of  contact  of  air. 

PercJiloride  of  Iron.— Atom.  Num.  SI -17— Symb.  l|Cl+Fe. 

A  compound  of  a  bright  yellowish  brown  colour,  crystallizing  in 
small  iridescent  plates  ;  it  is"  volatile  at  a  temperature  a  little  above 
212°  ;  and  when  thrown  into  water  is  converted  into  the  Permuriate 
of  Iron.  It  is  obtained  by  burning  iron  wire  in  an  atmosphere  of  chlo- 
rine, or  by  evaporating  the  permuriate  to  dryness.  This  muriate  is 
formed  by  digesting  the  peroxide  of  iron  in  muriatic  acid,  or  by  expos- 
ing the  protomuriate  to  air*  It  forms  the  basis  of  the  Tinctura  Muria- 
tis  Ferri  of  the  Pharmacopeia. 

IRON    AND    BROMINE. 

Bromides  of  Iron. — The  union  of  these  two  substances  may  be  ef- 
fected by  putting  into  a  porcelain  capsule  any  quantity  of  bromine 
with  about  twenty  times  its  weight  of  water,  and  adding  iron  filings  as 
long  as  any  action  continues,  accompanied  with  gentle  heat  and  agita- 
tion. If  the  solution  is  made  and  evaporated  to  dryness  in  close  ves- 
sels, a  protobromide  is  obtained  ;  but  if  freely  exposed  to  the  air  the 
perbromide  is  left. 

IRON    AND    IODINE. 

Iodide  of  Iron. — Iodide  and  iron  unite  and  form  a  brown  fusible  com- 
pound, which  decomposes  water,  and  passes  to  the  state  of  a  green 
Hydriodate  of  Iron. 

IRON    AND    SULPHUR. 

Two  compounds  of  these  bodies  are  well  known.  Gay  Lussac,  how- 
ever, contends  for  the  existence  of  three ;  Arfwedson  of  four ;  and 
Berzelius  of  five.  But  these  require  to  be  further  examined  before 
they  can  be  admitted  as  distinct  atomic  combinations. 


IRON,  273 

Protositlphuret  of  Iron. — Atom.  Num.  44 — Symb.  S+Fe. 

PROPERTIES.  A  yellow,  brittle  substance,  of  a  metallic  lustre,  which 
is  feebly  attracted  by  the  magnet,  and  by  exposure  to  air  and  moisture, 
is  gradually  converted  into  protosulphate  of  iron. 

This  sulphuret  exists  in  nature,  and  is  known  to  mineralogists,  by 
the  name  of  Magnetic  Iron  Pyrites.  It  may  be  prepared  artificially  by 
igniting  the  protosulphate  of  iron  with  charcoal  ;  or  still  more  conven- 
iently, by  heating  a  mixture  of  iron  filings  and  sulphur. 

Bisulpliuret  of  Iron. — Atom.  Num.  60 — Symb.  2S-f-Fe. 

An  abundant  natural  product  known  under  the  name  of  Iron  Py- 
rites, but  which  cannot  be  artificially  formed.  It  is  of  a  bronze  yel- 
low colour,  and  is  often  found  in  crystals  ;  when  heated  to  redness 
it  loses  half  its  sulphur,  and  becomes  converted  into  the  protosul- 
phuret. 

REFERENCES.  Proust,  en  the  native  and  artificial  sulphurets  of  Iron, 
Jour,  de  Phys.,  or  Rupert,  of  Arts,  1st  ser.  xvi.  411.  Thomson's  First  Prtn- 
ii.  191,  contains  a  description  of  a  Sesquisulphuret.  Arfwedson,  in  Ann.  of 
Phii.  xxiii.  341,  describes  two  new  sulphurets.  Gay  Lussac,  Ann.de  Chim. 
Ixxx.  170.  Berzelius,  Traite  de  Chim.  iii.  357. 


IRON    AND    PHOSPHORUS. 

Phosphuret  of  Iron. — A  brittle,  gray  compound,  which  acts  upon  the 
magnet,  and  is  formed  by  heating  the  phosphate  of  iron  with  charcoal, 
or  by  dropping  phosphorus  into  a  crucible  containing  red  hot  iron 
wire — Hatchett,  in  Phil.  Trans.  1804.  The  cold  short  iron  is  supposed 
to  owe  its  peculiar  properties  to  the  presence  of  phosphorus.  Dr. 
Thomson  describes  three  phosphurets  of  iron. — Inorg.  Ckem.  i.  501. 

IRON    AND    CARBON. 

Carburets  of  Iron. — Carbon  and  iron  unite  in  very  various  propor- 
tions ;  but  there  are  four  compounds  which  are  distinct  from  one  an- 
other, viz.  cast  or  pig  iron,  steel,  cast  steel,  and  graphite  or  plumbago. 

Cast  Iron,  being  the  name  applied  to  iron  as  it  flows  from  the  fur- 
nace in  which  it  is  reduced,  contains  among  other  ingredients,  a  very 
considerable,  but  variable  proportion  of  carbon,  amounting  sometimes, 
to  l-40th  of  its  weight.  In  this  state  it  is  neither  ductile  nor  mal- 
leable, but  very  brittle  ;  and  fuses  with  such  facility  at  a  red  heat  that 
it  cannot  be  welded.  It  is  highly  crystalline  and  its  texture  is  granu- 
lar. 

Cast  iron  may  be  converted  in  malleable  or  Wrought  Iron,  by  ex- 
posure in  a  reverbatory  furnace,  to  the  combined  action  of  heat  and 
air,  and  subjecting  the  iron  while  still  hot  to  the  operation  of  rolling 
or  hammering,  by  which  its  particles  are  approximated.  But  this, 
though  the  purest  iron  of  commerce,  still  contains,  according  to  Ber- 
zelius,  a  minute  quantity  of  carbon. 

There  are  three  varieties  of  cast-iron  commonly  distinguished  in 


274  IRON. 

commerce  ;  namely,  black  cast-iron  usually  called  No.  1,  mottled  cast- 
iron  called  No.  2,  and  white  cast-iron. 

M.  M.  Gay  Lussac  and  Wilson  have  published  the  results  of  a  series 
of  analyses  of  carbonaceous  irons,  which  show  the  carbon  in  the  bar 
irons  examined  to  vary  from  fourteen  to  twenty-nine,  and  in  the  steels 
from  sixty-two  to  ninety-three  ten-thousand  parts.  In  gray  cast-iron 
it  varied  from  sixteen  to  twenty-eight,  and  in  white  from  twenty -three 
to  twenty-seven  thousand  parts. — Jour,  of  Science,  1830. 

Steel  is  made  by  exposing  bars  of  the  purest  malleable  iron,  sur- 
rounded with  charcoal  in  powder,  to  a  long  continued  red  heat.  Dur- 
ing this  process,  the  iron  unites  with  about  l-150th  of  its  weight  of 
carbon,  and  acquires  new  properties.  It  is  much  harder  than  iron  ; 
is  more  sonorous  and  elastic,  and  takes  a  much  higher  polish,  though 
it  is  less  ductile  and  malleable.  It  bears  a  strong  red  heat  and  may 
be  welded  to  iron.  When  combined  with  an  additional  quantity  of 
carbon,  it  forms  Cast  Steel,  which  is  harder,  more  elastic  and  receives 
a  higher  polish  than  common  steel,  but  is  so  fusible  that  it  cannot  be 
welded. 

As  has  already  been  observed  [p.  165]  diamonds  when  heated  with 
soft  iron,  convert  it  into  steel  in  the  same  manner  as  charcoal. 

Steel  may  be  distinguished  from  pure  iron  by  applying  a  drop  of  di- 
lute muriatic  or  nitric  acid  to  the  surface,  when  the  carbon  which  it 
contains  will  be  exhibited  by  a  black  stain. 

Wootz,  or  Indian  steel,  which  is  so  valuable  for  the  purpose  of  mak- 
ing edge  tools,  owes  its  excellence  to  combination  with  a  minute  por- 
tion of  aluminum  and  silicium — [Faraday,  Brande's  Jour.  vii.  288J 
and  according  to  Stodart  and  Faraday,  steel  may  be  much  improved 
for  certain  purposes,  by  being  alloyed  with  silver,  platinum.  «fec. — 
Brande's  Jour.  ix.  319. 

Graphite  or  Plumbago,  also  known  by  the  name  of  Black  Lead,  has 
an  iron  gray  colour,  metallic  lustre,  and  granular  texture  ;  and  is  gen- 
erally stated  to  be  a  compound  of  95  per  cent,  of  carbon,  with  5  of  iron. 
But  this  is,  perhaps,  more  correctly  to  be  considered  as  a  pure  form 
of  carbon.  [See  p.  165.]  It  is  an  abundant  native  product,  and  is 
used  in  making  pencils  and  crucibles,  and  in  burnishing  iron  to  protect 
it  from  rust. 

REFERENCES.  Mushet  on  Iron  and  Steel,  TillocJCs  Phil.  Mag.  iL  The 
articles  Iron  Making,  by  D.  Mushet ;  and  Cutlery,  bij  Slodart,  in  the  Supple- 
ment to  the.  Encyclopedia  Britannica. 


IRON    AND    THE    METALS. 

According  to  Berzelius,  iron  forms  alloys  with  most  of  the  other  me- 
tals. \Traite,  de  Chim.  iii.  284-]  None  of  these,  however,  are1  of  much 
importance,  except  tin  plate,  which  will  be  described  in  the  section 
on  tin. 

Ferrocyanic  Acid. 

PROPERTIES.  This  acid  is  neither  volatile  nor  poisonous,  in  small 
quantities,  and  has  no  odour  ;  it  is  gradually  decomposed  by  exposure 


IRON.  275 

to  the  light,  forming  hydrocyanic  acid,  and  Prusian  blue,  but  it  is  far 
less  liable  to  spontaneous  decomposition  than  hydrocyanic  acid  ;  it  red- 
dens litmus  permanently  ;  unites"  with  bases  and  forms  salts  called 
Ferrocyanates  or  Triple  Prussiates  ;  it  separates  carbonic  and  acetic 
acids  from  their  combinations,  and  even  decomposes  some  salts  of  the 
more  powerful  acids. 

This  substance  has,  within  a  few  years,  been  the  subject  of  able  re- 
searches by  Mr.  Porrett,  Berzelius  and  Robiquet,  but  its  true  nature  is 
still  involved  in  some  obscurity.  The  view  of  Mr.  Porrett,  which  ap- 
pears to  be  most  consistent  with  the  phenomena,  is,  that  the  elements 
of  this  acid  are  carbon,  hydrogen,  nitrogen  and  metallic  iron,  and  he 
proposes  for  it  the  name  of  Ferruretled  C/iyazic  Acid. 

From  the  latest  and  best  experiments  on  this  subject  it  is  probable 
that  ferrocyanic  acid  is  composed  of 

Hydrogen,  2  atoms=  2  )          C  Hydrocyanic  Acid,  2  atoms  =54 

Iron,  1  atom  =28  >  or  of  ^ 

Cyanogen,  3  atoms  =78  )  (  Cyanide  of  Iron,      1  atom  =54 

108  108 

—Ann.  de  Chim.  et  de  Phys.  xvii.  197.  xxii.  322. 

PREPARATION  Mr.  Porrett  recommends  two  methods  for  obtaining 
ferrocyanic  acid,  by  one  of  which  it  is  procured  in  crystals,  and  by 
the  other  in  a  state  of  solution.  The  first  process  consists  in  dissolv- 
ing 58  grains  of  crystallized  tartaric  acid  in  alcohoi,  and  mixing  the 
liquid  with  50  grains  of  the  ferrocyanate  of  potassa,  dissolved  in  the 
smallest  possible  quantity  of  hot  water.  The  bitartrate  of  potassa  is 
precipitated,  and  the  clear  solution,  on  being  allowed  to  evaporate 
spontaneously,  gradually  deposites  ferrocyanic  acid  in  the  form  of 
small  cubic  crystals  of  a  yellow  colour.  In  the  second  process,  the 
ferrocyanate  of  baryta,  dissolved  in  water,  is  mixed  with  a  quantity 
of  sulphuric  acid,  which  is  precisely  sufficient  for  combining  with  the 
baryta.  The  insoluble  sulphate  of  baryta  subsides,  and  the  ferrocy- 
anic acid  remains  in  solution.  According  to  Mr.  Porrett,  every  ten 
grains  of  the  ferrocyanate  of  baryta  require  so  much  liquid  sulphuric 
acid  as  is  equivalent  to  2-53  grains  of  real  acid. 

REFERENCES.  Porrett  on  the  Pnissic  and  Prussous  Acids,  Repert.  Arts, 
%dser.  xvi.  232,  273.  Porrett  on  the  Ferruretted  Chy&zic  Acid.  Phil.  Trans, 
for  1814  and  1815.  Ann.  of  Phil.  v.  25.  xii.  102.  xiv.  295.  Robiquet,  Ann. 
de  Chim.  xii.  277,  or  Branded  Jour.  ix.  179.  Rerzelius,  in  Ann.  de  Chim. 
•et  de  Phys.  xv.  144,  or  Ann.  of  Phil,  xvii  and  xviii.  Robiquet^  Ann.  de 
C/tirn.  et  de  Phys.  xvii. 

SALTS    OF    IRON. 

Both  of  the  oxides  of  iron  combine  with  acids,  and  form  distinct 
classes  of  salts. 

Protonitrate  of  Iron. — Atom.  Num.  15-3 — Symb.   (5O+N) 
+(0+Fe)+7  Aq. 

PROPERTIES.  Crystallizes  in  rhomboidal  prisms,  transparent  and  of 
a  light  green  colour ;  reddens  vegetable  blues,  as  do  all  the  soluble 


276  IRON. 

gaits  of  iron  ;  has   a  sweetish  astringent  taste,  like  that  of  protosul- 
phate  of  iron,  but  harsher. 

PREPARATION.  This  salt  is  obtained  by  dissolving  iron  in  dilute  ni- 
tric acid,  till  the  acid  refuses  to  take  up  any  more  of  the  metal.  The 
solution  is  then  to  be  concentrated  under  the  exhausted  receiver  of  an 
air  pump,  over  sulphuric  acid. — Thomson's  First  Prin.  ii.  318. 

Persesquinitrate  of  Iron. — Jltom.  Num.  193 — Syrnb.  1J 
(5O+ N)+(l £O+Fe.)+8  Aq. 

When  nitrate  of  iron,  as  above  prepared,  is  exposed  to  the  at- 
mosphere, it  passes  to  the  state  of  that  in  which  the  oxide  is  at  the 
maximum  ;  or  we  may  obtain  this  salt  by  leaving  nitric  acid  for  a  long; 
time  in  contact  with  protoxide  of  iron.  Crystals  form  spontaneously 
in  the  liquid,  which  are  at  first  transparent  and  colourless,  but  become 
brown  by  keeping ;  their  taste  is  acid  and  they  redden  vegetable  blues- 
According  to  the  analysis  of  Dr.  Thomson  they  are  constituted  as 
above.— First  Prin.  ii.  328. 

Protosvlphatt  of  Iron.— Atom.    Num.  139— Symb.  (3O+S) 
+(0+Fe.)+7  Aq. 

PROPERTIES.  This  salt,  commonly  known  by  the  name  of  Green  Vit- 
riol or  Copperas,  has  a  strong  styptic,  inky  taste ;  it  reddens  vegetable 
blues  ;  is  insoluble  in  alcohol,  but  soluble  in  two  parts  of  cold,  and  in 
three-fourths  of  its  weight  of  boiling  water;  it  oceurs  in  right  rhombic 
prisms,  which  are  transparent  and  of  a  pale  green  colour;  in  its  anhy- 
drous state  it  is  a  dirty  white  powder. 

This  salt  is  sometimes  found  native,  associated  with  iron  pyrites  ;  it 
is  formed  artificially  by  the  action  of  dilute  sulphuric  acid  on  metallic 
iron,  or  by  exposing  the  protosulphuret  of  iron  in  fragments  to  the 
combined  agency  of  air  and  moisture.  It  is  largely  used  in  the  arts, 
especially  in  'dyeing,  and  in  the  manufacture  of  ink-powder. — See 
Aikin's  Ohem.  Diet,  and  Henry's  Chcm.  ii.  33. 

PersesquisidpJiate  of  Iron. — Atom.  Num.  100 — Syinb.    1  £ 
(30+S)+(lJO+Fe.) 

When  a  portion  of  protosulphate  of  iron  is  peroxidized  by  means  of 
nitric  acid,  and  cautiously  concentrated  till  the  whole  of  the  nitric 
acid  is  dissipated,  we  obtain  a  red  coloured  mass,  which  dissolves  only 
partially  in  water.  The  solution  has  a  red  colour  with  a  tint  of  yel- 
low— the  taste  is  astringent  and  very  harsh.  When  evaporated  to  dry- 
ness  it  speedily  absorbs  moisture,  and  deliquesces  into  a  liquid.  Alco- 
hol dissolves  it  readily  and  it  strongly  reddens  vegetable  blues  ;  and 
this  is  the  salt  to  which  Berzelius  and  Thomson  have  assigned  the 
above  constitution. 

The  portion  remaining,  after  the  above  salt  has  been  extracted,  is 
a  red  coloured  powder,  destitute  of  taste  and  insoluble  in  water,  to 
which  Dr.  Thomson  has  given  the  name,  Pertetr  a  sulphate  of  Iron — con- 
sisting of  I  atom  sulphuric  acid  and  4  atoms  peroxide  of  iron. 

When  the  persulphate  of  iron  is  mixed  with  the  sulphate  of  potassa. 


IRON.  277 

and  the  solution  allowed  to  crystallize  by  spontaneous  evaporation, 
crystals  are  obtained  similar  to  common  alum  in  form,  colour,  taste 
and  composition.  In  tbis  double  salt,  the  sulphate  of  alumina  is  re- 
placed by  persulphate  of  iron,  with  which  it  is  isomorphous. 

A  similar  double  salt  may  be  made  with  a  mixture  of  sulphate  of 
ammonia  and  persulphate  of  iron. 

Protophosphate  of  Iron,  is  a  salt  of  a  beautiful  pale  blue  colour,  sola 
ble  in  most  acids,  and  precipitated  again  by  ammonia  without  change. 
It  is  found  native  both  in  the  state  of  powder  and  of  fine  blue  crystals 
— and  may  be  prepared  artificially  by  mixing  solutions  of  protosul- 
phate  of  iron  and  phosphate  of  soda.  It  consists  of  one  atom  of  pro- 
toxide of  iron,  and  one  atom  of  acid,  with  various  proportions  of  wa- 
ter. 

There  are  three  species  of  phosphate  of  iron  which  occur  native, 
viz.  Hydrated  phosphate  of  iron,  Hydrated  Subsesquiphosphate  and 
Hydrated  Diphosphate. 

Perphosphatcoflron,  is  a  yellowish  white,  insoluble  powder,  formed  by 
mingling  the  solutions  of  persulphate  of  iron  and  phosphate  of  soda. 

Protocarbonate  of  Iron. — Atom.  Num.  58 — Symb.  (2O+C) 

+(o+Fe.) 

This  salt  exists  abundantly  in  nature.  It  occurs  sometimes  massive, 
sometimes  crystallized  in  rhombs  or  hexagonal  prisms.  It  is  also  con- 
tained in  most  of  the  chalybeate  mineral  waters,  being  held  in  solution 
by  free  carbonic  acid.  It  is  very  difficult  to  form  it  artificially. 

The  Subcarbonatc  of  Iron,  of  the  London  Pharmacopeia,  consists  of 
about  40  per  cent,  carbonate  of  iron,  and  60  of  the  peroxide. — Phillips. 

We  are  not  acquainted  with  any  compound  of  carbonic  acid  with 
the  peroxide  of  iron. 

The  mineral  known  by  the  name  of  iron  stone,  or  day  iron  stone, 
from  which  almost  all  the  immense  quantity  of  iron  manufactured  in 
England  is  smelted,  is  a  carbonate  of  iron  intermixed  with  more  or  less 
clay,  coal  and  sometimes  limestone. 

Silicate  of  Iron. — The  brown  coloured  hard  slag  from  the  smelting 
of  copper  ore,  is  either  a  silicate  or  bisilicate  of  iron,  according  to  cir- 
cumstances. There  occur  native  no  fewer  than  six  species  of  silicated 
iron  minerals. 

Ferrocyanate  of  Potassa.  sometimes  called  Triple  Prussiate  of  Potas- 
sa—A  perfectly  neutral  salt,  which  is  soluble  in  less  than  its  own 
weight  of  water,  and  forms  large  transparent  four-sided  tabular  crys- 
tals, of  a  lemon-yellow  colour  ;  it  is  inodorous,  has  a  slightly  bitter 
taste,  but  quite  different  from  that  of  hydrocyanic  acid,  and  is  perma- 
nent in  the  air  ;  when  heated  to  redness  it  is  decomposed,  nitrogen 
gas  is  disengaged,  and  cyanide  of  potassium,  mixed  with  carburet  of 
iron,  remains  in  the  retort. 

This  compound  is  best  formed  by  digesting  pure  ferrocyanate  of  iron 
in  potassa,  until  the  alkali  is  neutralized,  by  which  means  the  perox- 
ide of  iron  is  set  free,  and  a  yellow  liquid  is  formed,  which  yields 
crystals  of  the  ferrocyanate  of  potassa  by  evaporation.  It  is  made  on 
a  large  scale,  in  the  arts,  by  igniting  dried  blood  or  other  animal  mat- 
ters, such  as  hoofs  and  horns,  with  potash  and  iron. 

There  is  much  diversity  of  opinion  concerning  the  constitution  of 
this  salt.  In  the  form  of  crystals,  it  is  most  probably,  as  Berzelius 
supposes,  a  double  cyanide  of  potassium  and  iron  ;  in  solution,  aferro- 


278  IRON. 

eyanate  of  potassa. — See  a  discussion  on  this  subject,  ly  Mr.  R.  Phil- 
lips, in  Phil.  Mag.  and  Ann.  i.  110,  and,  also  the  references  under  Ferro- 
cyanic  Acid. 

The  ferrocyanate  of  potassa  is  employed  in  the  preparation  of  seve- 
ral compounds  of  cyanogen,  and  as  a  reagent  for  detecting  the  presence 
of  iron  and  other  substances. 

Red  ferrocyanate  of  Potassa — obtained  by  passing  chlorine  gas  int° 
a  moderately  strong  solution  of  common  ferrocyanate  of  potassa) 
which  is  to  be  continued  until  the  solution  ceases  to  produce  any  ef" 
feet  when  added  to  a  solution  of  peroxide  of  iron.  The  liquor  is  then 
to  be  concentrated  to  two-thirds  of  its  volume,  and  set  aside  in  a  mode- 
rately warm  stove  to  crystallize  :  after  some  time,  brilliant  and  slender 
yellow  crystals  are  obtained  in  the  form  of  a  rose  ;  by  a  second  crys- 
tallization, very  long  needle-form  crystals  are  procured  in  tufts. — 
These  crystals  are  ruby-coloured,  transparent  and  very  brilliant ;  their 
form  appears  to  be  elongated  octahedrons. 

The  principal  character  of  this  salt  is  that  of  indicating  the  proto- 
salts  of  iron,  precipitating  them  blue  or  green,  according  to  the  pro- 
portion in  solution  ;  and  on  the  contrary  not  precipitating  the  per  salts 
of  iron.  This  reagent,  according  to  M.  Girardin,  is  much  more 
sensible  than  the  common  ferrocyanate  of  potassa,  for  ft  is  capable  of 
detecting  one  90,000th  of  protoxide  of  iron,  while  the  latter  salt  does 
not  detect  more  than  one  1800th  of  the  protoxide. 

Ferrocyanate  of  Baryta,  is  soluble  in  water,  and  forms  yellow  crys- 
tals by  evaporation.  It  is  prepared  by  digesting  purified  Prussian  blue 
with  a  solution  of  pure  baryta,  and  is  used  in  the  formation  of  ferro- 
cyanic  acid. 

Ferrocyanate  of  the  Peroxide  of  Iron. — This  substance,  which  forms 
the  basis  of  Pi-ussian  Blue,  is  insipid  and  inodorous,  insoluble  in  water 
and  in  acids,  unless  they  are  concentrated  and  heated  ;  it  is  rendered 
white  by  strong  sulphuric  acid  ;  is  decomposed  by  the  alkalies  and  al- 
kaline earths,  which  unite  with  the  ferrocyanic  acid,  and  liberate  the 
peroxide  of  iron  ;  is  also  decomposed  by  peroxide  of  mercury,  giving 
rise  to  bicyanide  of  mercury  ;  at  a  temperature  above  307°  F.  it  takes 
fire  and  burns  like  tinder,  leaving  from  54  to  60  per  cent,  of  the  oxide 
of  iron. — Henry. 

This  compound,  which  was  an  accidental  discovery  of  a  colour- 
maker  of  Berlin,  in  1710,  is  formed  by  mixing  ferrocyanate  of  potassa 
with  a  persalt  of  iron  in  slight  excess,  and  washing  the  precipitate 
with  water.  The  Prussian  blue,  of  which  this  is  the  colouring  mate- 
rial, is  prepared  by  heating  to  redness  dried  blood,  or  other  animal  sub- 
stances, with  an  equal  weight  of  pearlash,  until  the  mixture  has  ac- 
quired a  pasty  consistence.  The  residue,  which  consists  chiefly  of 
cyanide  of  potassium  and  carbonate  of  potassa,  is  dissolved  in  water, 
and  after  being  filtered,  is  mixed  with  a  solution  of  two  parts  of  alum 
and  one  part  of  the  protosulphate  of  iron.  A  dirty  greenish  precipi- 
tate ensues,  which  absorbs  oxygen  from  the  atmosphere,  and  passes 
through  different  shades  of  green  and  blue,  until  at  length  it  acquires 
the  proper  colour  of  the  pigment. 

The  chemical  changes  which  take  place  in  this  process  are  of  a  very 
complicated  nature,  and  do  not  appear  to  be  understood.  According 
to  Dr.  Turner  the  precipitate  which  is  at  first  thrown  down,  is  occa- 
sioned by  the  potassa,  and  consists  chiefly  of  alumina  and  the  protox- 
ide of  iron.  The  ferrocyanic  acid  is  generated  by  the  protoxide  re- 
acting upon  some  of  the  hydrocyanic  acid,  so  as  to  form  water  and 


ZINC.  279 

cyanide  of  iron,  the  latter  of  which  then  unites  with  undecomposed 
hydrocyanic  acid.  The  ferrocyanic  acid,  thus  produced,  combines  with 
oxide  of  iron  ;  and  when  the  latter  has  attained  its  maximum  of  oxi- 
dation, the  compound  acquires  its  characteristic  blue  tint.  This 
chemist  controverts  the  opinion  of  Dr.  Thomson,  that  the  protoxide  of 
iron  enters  into  the  composition  of  Prussian  blue.  He  states  that,  in 
every  good  specimen  of  Prussian  blue  which  he  examined,  the  ferro- 
cyanic acid  was  in  combination  with  peroxide  of  iron  only. 

REFERENCES.  The  first  published  account  of  the  method  of  preparing 
Prussian  Blue,  will  be  found  in  the  Phil.  Trans,  xxxiii.  Proust's  Essay  on 
Prussian  Blue,  Jour,  de  Phys.  or  Repert.  of  Arts,  1st  ser.  xiiL  180.  Dr. 
Cooper  on  the  Manufacture  of  Prussian  Blue, ^Emporium  of  Arts,  iii.  456» 
On  the  same  subject,  see  Aikiti's  Chem.  Diet.  ii.  Zollickoffer  on  the  medicinal 
properties  of  the  Prussiate  or  ferrocyanate  of  Iron. 

TESTS  OF  THE  SALTS  OF  IRON.  The  salts  of  iron  are  mostly  soluble  in 
water.  Those  in  which  the  basis  is  the  protoxide,  afford  a  precipitate 
of  a  white  hydrate,  upon  the  addition  of  the  pure  alkalies,  and  a  white 
carbonate,  by  alkaline  carbonates,  arid  a  white  ferrocyanate,  by  ferro- 
cyanate of  potassa.  The  two  former  precipitates  become  first  green 
and  then  red  ;  and  the  latter  green  and  blue  by  exposure  to  the  air. 

The  persalts  give  a  blue  precipitate  with  ferrocyanate  of  potassa, 
blood  red  with  the  sulphocyanate  of  potassa,  and  deep  black  with  in- 
fusion of  galls. 

The  separation  of  the  oxides  of  iron  and  manganese  is  one  of  the 
most  complex  problems  in  analytical  chemistry,  and  has  engaged  the 
attention  of  many  chemists.  Berzelius  and  Rose  recommend,  for 
this  purpose,  succinate  of  soda,  or  ammonia,  which  throws  down  the 
iron,  and  leaves  the  manganese.  For  directions  concerning  the  em- 
ployment of  this  and  other  means  of  separating  the  oxides  of  these 
metals,  see  Rose's  Manual,  55,  and  Henry's  Chem.  ii.  590. 

SECTION  XVI. 

ZINC. 
Atom.  Num.  32-5—  Symb.  Zn— Sp.  gr.  7. 

Zinc  has  long  been  known  as  a  metal  in  China  and  India,  but  its 
extraction  from  its  ores  is  a  comparatively  recent  discovery  in  Europe. 
Henckel  first  extracted  zinc  from  calamine  about  the  year  1721 ;  Von 
Swab  obtained  it  by  distillation  in  1742,  and  Margraff  published  a  pro- 
cess in  the  Berlin  Memoirs  in  1746. 

PROPERTIES.  This  metal  is  of  a  brilliant  white  colour  with  a  shade 
of  blue;  it  is  hard,  being  acted  on  by  the  file  with  difficulty  ;  at  low 
or  high  degrees  of  heat  it  is  brittle  :  but  at  temperatures  between  210° 
and  300°  F.  it  is  both  malleable  and  ductile,  a  property  which  enables  it 
to  be  hammered  into  sheets  of  considerable  thinness  ;  it  fuses  at  680°  F. 
and  when  slowly  cooled,  forms  regular  crystals  ;  in  its  ordinary  state 
it  may  be  pulverized  when  hot,  in  a  heated  iron  mortar,  the  pestle  being 
also  healed. — Faraday. 

NATIVE  STATE  AND  EXTRACTION.  The  zinc  of  commerce,  sometimes 
called  Spelter,  is  obtained  either  from  Calamine,  the  native  carbonate 
of  zinc,  or  from  the  native  sulphuret,  the  Zinc  Blende  of  mineralogists. 


280  ZINC. 

It  is  procured  from  the  former  by  heat  and  carbonaceous  matters  ;  and 
from  the  latter  by  a  similar  process  after  the  ore  has  been  previously 
oxidized  by  roasting,  that  is,  by  exposure  to  the  air  at  a  low  red  heat. 
When  first  extracted  from  its  ores,  it  is  never  quite  pure  ;  but,  contains 
charcoal,  sulphur,  and  several  metals  in  small  quantity.  It  may  be 
freed  from  these  impurities  by  distillation, — by  exposing  it  to  a  white 
heat  in  an  earthern  retort,  to  which  a  receiver  full  of  water  is  adapted. 
USES.  Metallic  zinc,  is  employed  in  the  laboratory,  for  the  con- 
struction of  voltaic  instruments. — It  has  also  been  proposed  for  the 
purpose  of  culinary  vessels,*  pipes  for  conveying  water,  sheathing  for 
ships,  &c.  but  it  is  easily  acted  on  by  the  weakest  acids,  and  is  even- 
tually, though  slowly,  oxidized  by  long  exposure  to  air  and  moisture. 
It  is  hence  unfit  for  these  uses.  Zinc  is,  however,  employed  with  ad- 
vantage when  rolled  into  larjge  plates,  as  a  substitute  for  lead  and 
slates  in  the  covering  of  buildings. 

REFERENCES.  On  the  treatment  necessary  to  render  Zinc  malleable  and 
ductile,  see  Sylvester^  in  Phil.  Mag.  xxiii.,  and  the  Patents  granted  to  him 
in  Rep.  of  Arts,  %d  ser.  vii.  404.  ix.  251.  On  the  danger  attending  the  use 
of  Zinc  for  culinary  purposes,  and  for  measures  for  liquids,  fyc.  see  the  Re- 
ports of  the  Medical  Faculty  of  Paris,  fyc.  Ann.  de  Chiin.  or  Rep.  of  Arts, 
2d  ser.  xxiii.  178,  and  xxv.  247.  Beck's  Med.  Juris.  467. 

ZINC  AND  OXYGEN. 

Oxide  of  Zinc.— Atom.  Num.  4(V5 — Symb.  O+Zn. 

Formerly  called  Flowers  of  Zinc — Pompholix — Nihil  album — Philo- 
sopher's Wool,  fyc. 

PROPERTIES.  White  at  common  temperatures  ;  but  when  heated  to 
low  redness  il  assumes  a  yellow  colour,  which  gradually  disappears  on 
cooling  ;  it  is  fixed  in  the  fire  and  very  difficult  of  fusion  ;  is  insoluble 
in  water,  and  therefore  does  not  affect  the  blue  colour  of  plants  ;  it  is 
a  strong  salifiable  base,  forming  regular  salts  with  acids,  most  of  which 
are  colourless. 

NATIVE  STATE  AND  PREPARATION.  This  substance,  which  is  rare  in 
nature,  is  found  at  Franklin,  New-Jersey.  It  may  be  formed  by  fusing 

*  Vessels  of  zinc  have  long  been  known  to  be  favourable  for  obtaining;  a 
superior  quantity  of  cream  from  new  milk  placed  in  them,  and  patents  for  the 
manufacture  of  dairy  utensils  from  this  metal  have  been  taken  out  in  England 
and  al>o  in  this  country.  The  increase  i  i  the  quantity  of  cream  is  probably 
owing  to  the  fact  that  the  acetic  acid  developed  in  milk  by  heat  and  rest,  is 
taken  up  by  the  zinc;  and  thus  the  coagulation  of  the  milk  which  would  be 
produced  by  the  action  of  the  free  acetic  acid  is  prevented,  and  the  milk  by 
remaining  more  perfectly  fluid,  admits  the  easy  ascent  of  the  suspended  cream. 
But  the  miik  must  at  the  saint;  time  become  impregnated  with  a  soluble  and 
deleterious  salt  of  zinc,  and  is  unfit  for  use.  Indeed  the  ease  with  which  this 
metal  is  acted  on  by  the  weakest  acids,  constitutes  an  insurmountable  objec- 
tion to  its  employment  for  culinary  purposes. — See  Lardner^s  Cyclopaedia, 
Manufactures  in  Metal. 


ZINC.  281 

zinc  in  open  vessels.  When  the  metal  is  heated  to  full  redness  in  a 
covered  crucible,  it  bursts  into  a  flame  as  soon  as  the  cover  is  removed, 
and  burns  with  a  brilliant  white  light.  The  combustion  ensues  with 
such  violence,  that  the  oxide  as  it  is  formed  is  mechanically  carried  up 
into  the  air,  in  which  state  it  has  a  considerable  resemblance  to  carded 
wool.  By  heating  metallic  zinc  in  an  atmosphere  of  aqueous  vapour, 
cautiously  regulating  the  heat  so  as  not  to  fuse  the  metal,  M.  Haldat 
has  obtained  crystals  of  oxide  of  zinc,  of  a  honey  colour,  almost  trans- 
parent, and  of  a  rhomboidal  form. — Ann.  de  Chim.  xlvi.  72. 

Hydrated  Oxide  of  Zinc — may  be  obtained  in  crystals  by  uniting  a 
rod  of  zinc  and  iron,  and  placing  them  in  caustic  ammonia  in  a  close 
vessel.  Gas  is  developed,  and  in  a  few  days  the  inside  of  the  vessel  is 
covered  with  small  transparent  crystals,  which  are  permanent  in  the 
air,  and  consist  of  one  atom  oxide  of  zinc-f-°ne  atom  water=49*5. 
[Journ.  of  Science,  1830,  p.  204.]  The  oxide  is  also  precipitated  in 
the  form  of  a  hydrate,  by  the  addition  of  a  solution  of  pure  potassa  or 
ammonia  to  a  solution  of  the  sulphate  of  zinc. 

According  to  Berzelius  there  is  a  suboxide  of  Zinc,  and  Thenard  de- 
scribes a  deutoxide;  but  these  do  not  appear  to  be  recognized  by  other 
chemists. 

ZINC  AND  CHLORINE. 

Chloride  of  Zinc.— Atom.  Num.  67-95— Symb.  Cl+Zn. 

Formerly  called  Butter  of  Zinc. 

PROPERTIES.  A  compound  fusible  under  a  dull  red  heat,  and  on  cool- 
ing goes  through  several  degrees  of  consistency,  being  viscid  before  it 
becomes  solid  ;  it  is  very  deliquescent  and  by  the  action  of  water  pro- 
duces a  Muriate  of  Zinc. 

This  chloride  is  obtained  by  burning  leaf  zinc  in  chlorine  gas,  or  by 
adding  muriatic  acid  to  zinc,  evaporating  the  residue  to  dry  ness  and 
then  heating  it  to  redness  in  a  glass  tube.  According  to  Dr.  Thom- 
son, if  the  application  of  heat  be  stopped  at  the  right  point,  a  muriate 
of  zinc  may  be  obtained,  perfectly  free  from  water,  of  which  this  com- 
pound and  muriate  of  ammonia  are  the  only  examples. — First  Prin.  ii. 

ZINC    AND    IODINE. 

Iodide  of  Zinc. — Atom.  Num.  158'5 — Symb.  I-J-Zn. 

A  fusible  and  volatile  crystalline  compound  which,  when  exposed  to 
the  air,  deliquesces  and  is  converted  into  Hydriodatc,  of  Zinc.  It  is 
formed  by  the  union  of  iodine  and  zinc. 

ZINC  AND  SULPHUR. 

SulpJmret  of  Zinc.— Atom.  Num.  48-5—  Symb.  S+Zn. 

This  compound  exists  in  nature  under  the  name  of  Blende,  and  is 
frequently  found  in  dodecahedral  crystals,  or  in  forms  allied  to  the 
dodecahedron.  Its  structure  is  lamellated,  its  lustre  adamantine,  and 
its  colour  variable,  being  sometimes  yellow,  red,  brown  or  black.  It 


282  ZINC. 

may  be  made  artificially  by  heating  to  redness  a  mixture  of  oxide  of 
zinc  and  sulphur,  by  decomposing  sulphate  of  zinc  by  charcoal,  or  by 
drying  the  white  precipitate  obtained  on  adding  hydrosulphuret  of  am- 
monia to  a  salt  of  zinc. 

The  native  black  Blende,  called  by  the  miners  Black  Jack,  is  an 
abundant  mineral,  and  important  as  the  source  of  the  pure  metal, 
which  is  obtained  by  roasting  the  ore,  and  afterwards  exposing  it  to 
heat  in  proper  distillatory  vessels  mixed  with  charcoal. 

REFERENCES.  Thomson,  on  the  composition  of  Blende,  Ann.  of  Phil.  iv. 
89.  On  the  methods  of  extracting  the  metal  from  this  and  other  ores  of  Zinc, 
see  Bishop  Watson's  Chem.  Essays,  iv.  1.  Bergman's  Works,  \\.  309,  and 
Aikin's  Chem.  Diet.  ii. 

Phosphuret  of  Zinc,  is  a  compound  of  a  whitish  colour,  and  a  me- 
tallic lustre  not  unlike  lead.  It  has  some  malleability,  exhales  a  phos- 
phoric smell,  and  at  a  high  degree  of  heat,  burns  like  common  zinc. 

Cyanide  or  Cyanuret  of  Zinc.  —  This  compound  is  obtained  by  Pelletier 
by  precipitating  sulphate  of  zinc  by  hydrocyanate  of  potassa  ;  forming 
a  triple  hydrocyanate  of  zinc,  which  being  well  dried,  and  calcined  at  a 
dull  red  heat,  is  converted  into  a  cyanide  of  zinc.  It  always  contains, 
however,  cyanide  of  potassium. 

The  above  or  a  similar  compound  has  of  late  been  employed  in  Ger- 
many, instead  of  the  hydrocyanic  acid,  and  it  has  obtained  the  reputa- 
tion of  possessing  decided  vermifuge  powers. — Ma yendie's  Formulary. 

ZINC    AND    THE    METALS. 

Zinc  is  capable  of  furnishing  alloys  with  most  of  the  other  rnetals. 
Of  these  the  most  useful,  brass,  will  be  mentioned  in  treating  of  cop- 
per. With  mercury  it  forms  an  amalgam,  used  for  exciting  electrical 
machines. 


SALTS  OF  ZIXC. 

lodateof  Zinc,  falls  down  in  an  insoluble  powder,  when  iodate  of  po- 
tassa is  added  to  sulphate  of  zinc. 

Nitrate  of  Zinc.— Atom.  Num.   US'5~Symb.  (5O+J\)+ 
(O-fZn)+6Aq. 

A  salt  with  an  exceedingly  disagreeable  taste,  and  which  may  be 
obtained  with  difficulty  in  Hat  four-sided  prisms,  which  deliquesce  with 
great  rapidity.  It  is  prepared  by  the  action  of  dilute  nitric  acid  upon 
zinc,  and  subsequent  evaporation. 

Sulphite  of  Zinc. — A  crystallizable  salt,  readily  soluble  in  water,  but 
not  in  alcohol  ;  obtained  by  dissolving  zinc  in  sulphurous  acid. 

Sulphate  of  Zinc.— Atom.   Num.   143-5—  Symb.    (3O+S)+ 

(0+Zn)+7  Aq. 
SYN.      White  Vitriol. 

PROPERTIES.  Taste  bitter  and  styptic  ;  colour  white ;  it  crystalli- 
zes by  spontaneous  evaporation,  in  transparent  flattened  four-sided 


ZINC.  283 

prisms,  the  primary  form  of  which  is  a  right  rhombic  prism  andisomor- 
phous  with  epsom  salts  ;  the  crystals  dissolve  in  two  parts  and  a  half 
of  cold,  and  are  still  more  soluble  in  boiling  water;  it  reddens  vegeta- 
ble blues,  though,  in  composition,  strictly  a  neutral  salt  ;  when  the  crys- 
tals are  deposited  from  a  hot  solution,  they  only  contain,  according  to 
Thomson,  three  proportions  of  water. 

NATIVE  STATE  AND  PREPARATION.  This  salt  is  found  native  in  pla- 
ces where  the  sulphuret  of  zinc  occurs  ;  being  probably  the  result 
of  the  decomposition  of  that  ore.  It  is  prepared  artificially  by  the  ac- 
tion of  dilute  sulphuric  acid  upon  metallic  zinc  during  the  process  for 
preparing  hydrogen  gas  ;  but  for  the  purposes  of  commerce,  it  is  made 
by  roasting  the  native  sulphuret  of  zinc  in  a  reverbatory  furnace.  The 
English  white  vitriol,  however,  is  prepared  for  the  most  part  by  the  di- 
rect action  of  sulphuric  acid  on  metallic  zinc,  and  is  much  purer  than 
that  obtained  by  the  decomposition  of  the  sulphuret.—  .4zA;i7i's  Chem, 
Diet.  ii. 

ADULTERATION.  Sulphate  of  zinc  is  almost  always  contaminated 
with  iron,  and  often  with  copper  and  lead.  Hence  the  yellow  spots 
which  are  visible  on  it  ;  and  hence  also  the  reason  why  its  solution  in 
water  lets  fall  a  dirty  brown  sediment.  It  may  be  purified  by  dissolv- 
ing it  in  water,  and  putting  into  the  solution  a  quantity  of  zinc  filings  ; 
taking  care  to  agitate  occasionally.  The  zinc  precipitates  the  foreign 
metals  and  takes  their  place.  The  solution  is  then  to  be  filtered  and 
the  sulphate  of  zinc  may  be  obtained  from  it  in  crystals  by  proper  evap- 
oration. —  Thomson. 

ACTION  ON  THE  ANIMAL  ECONOMY.  In  the  dose  of  a  scruple  or  a 
drachm,  sulphate  of  zinc  is  the  most  immediate  emetic  we  possess  ; 
and  it  is  to  be  inferred,  that  if  larger  doses  are  rejected,  as  is  the  fact, 
with  equal  rapidity,  they  will  in  general  cause  no  more  harm  than  the 
medicinal  dose.  In  some  instances,  however,  persons  have  suffered 
severely  from  over-doses  of  this  salt,  and  a  few  have  even  perished- 
It  has  also  been  said  to  have  proved  fatal  when  applied  externally.  — 
Christison  on  Poisons,  375.  Orfila,  Toxicologie  Generate. 

Phosphate  of  Zinc  __  Atom.  Num.  96-2—  Symb.  (2JO+PJ  + 
(  0+Zn.) 

A  white  tasteless  powder,  insoluble  in  water  and  without  effect  on 
vegetable  blues.  It  is  obtained  by  boiling  carbonate  of  zinc  in  phos- 
phoric acid,  after  the  acid  has  been  saturated  in  the  cold  and  applying 
heat  to  the  resulting  mass. 

Dr.  Thomson  describes  a  Eiphosphate  of  Zinc,  formed  by  dissolving 
carbonate  oT  zinc  in  excess  of  phosphoric  acid. 

Carbonate  of  Zinc.  —  Atom.  Num.  SQ'5—Symb.  (2O+C)+ 


A  white  and  tasteless  salt,  found  in  nature,  and  commonly  known 
by  the  name  of  Calamine,  which  occurs  either  anhydrous  and  crystal- 
lized, or  amorphous,  and  most  commonly  stalactitical  ;  in  which  state7 
each  atom  of  the  carbonate  is  united  with  an  atomfof  water. 

It  is  artificially  prepared  by  adding  carbonate  of  potassa  to  sulphate 
of  zinc.  After  the  precipitate  is  well  washed  and  dried,  it  is  consti- 


284  TIN. 

tuted  as  above  stated  ;  but  it  is  difficult  to  obtain  it  with  exactly  the 
due  proportion  of  water.     If  dryed  at  212°  F.  it  is  anhydrous. 

Ferrocyanate  of  Zinc  appears  as  a  yellowish  white  precipitate  on  add- 
ing ferrocyanate  of  potassa  to  sulphate  of  zinc. 

TESTS  OF  THE  SALTS  OF  ZINC.  The  salts  of  zinc  are  mostly  soluble 
in  water,  and  the  solutions  are  colourless  and  transparent ;  they  are 
not  precipitated  by  hydriodic  acid.  Potassa,  soda  and  ammonia,  form 
white  precipitates,  soluble  in  excess  of  the  alkali  and  in  sulphuric  acid. 
Hydrosulphuret  of  ammonia  causes  a  white  precipitate,  which  is  either 
a  hydrosulphuret  of  the  oxide  of  zinc,  or  a  hydrated  sulphuret  of  the 
metal.  The  soluble  phosphates,  carbonates  and  borates,  produce  white 
precipitates. 

SECTION  XVII. 
TIN. 

Atom.  Num.  57'9—Symb.  Sn.*  Sp.  gr.  7-9. 

This  metal  has  been  known  from  the  remotest  ages.  It  was  in  com- 
mon use  in  the  time  of  Moses,  and  was  obtained  at  a  very  early  period 
from  Spain  and  Britain,  by  the  Phenicians. 

PROPERTIES.  Tin  has  a  white  colour,  and  a  lustre  resembling  silver  ; 
is  not  oxidized  by  the  combined  agency  of  air  and  moisture,  though 
the  brilliancy  of  its  surface  is  soon  impaired  by  exposure  to  the  atmos- 
phere ;  it  is  quite  malleable,  for  the  thickness  of  common  tin-foil  does 
not  exceed  1 -1000th  of  an  inch  ;  it  is  soft  and  inelastic,  and  when  bent 
backwards  and  forwards,  emits  a  peculiar  crackling  noise  ;  at  442°  F. 
it  fuses,  and  if  exposed  at  the  same  time  to  the  air,  its  surface  tar- 
nishes, and  a  gray  powder  is  formed  ;  when  heated  to  whiteness,  it 
takes  fire  and  burns  with  a  white  flame,  being  converted  into  the  per- 
oxide of  tin. 

EXTRACTION.  The  tin  of  commerce,  known  by  the  name  of  Block 
and  Grain  Tin,  is  procured  from  the  native  oxide  by  means  of  heat  and 
charcoal.  The  best  grain  tin  is  almost  chemically  pure,  containing, 
according  to  Dr.  Thomson,  very  minute  quantities  of  copper  and  iron, 
and  occasionally  of  arsenic.  [Awn.  of  Phil  x.  166.]  According  to 
Thenard,  the  tin  from  Malacca  is  the  only  kind  which  is  perfectly 
pure.  [Traite  de  Chim.  i.  372.]  Tin  foil  is  said  to  be  almost  always 
a  compound  of  tin  and  lead. 

TIN  AND  OXYGEN. 

Tin  appears  to  be  susceptible  of  two  degrees  of  oxidation.  Both 
these  oxides  form  salts  by  uniting  with  acids;  but  they  are  likewise  ca- 
pable of  combining  with  alkalies. 

Protoxide  of  Tin. — Atom.  Num.  65  9 — Symb.  O+Sn. 
PROPERTIES.     A  powder  of  a  gray  colour,  indecomposable  by  heat ; 
*  From  the  htin  word  Stannum. 


TIN.  285 

Jt  is  insoluble  in  water  ;  when  slightly  heated  in  contact  with  atmos- 
pheric air  or  oxygen  gas,  it  is  converted  into  the  peroxide  with  the 
evolution  of  heat  and  light  ;  its  salts  not  only  attract  oxygen  from  the 
air,  but  act  as  powerful  deoxidizing  agents  ;  when  added  to  a  solution 
of  gold,  it  occasions  a  purple  coloured  precipitate,  the  purple  of  Cassius, 
by  which  this  oxide  may  be  recognized  with  certainty. 

PREPARATION.  This  oxide  may  be  prepared  by  keeping  tin  for 
sometime  in  a  state  of  fusion  in  an  open  vessel.  It  may  also  be  obtain- 
ed by  precipitation  from  the  protomuriate  of  tin.  But  it  is  difficult  to 
obtain  it  pure  in  consequence  of  the  great  attraction  which  it  has  for 
oxygen,  and  its  consequent  conversion  into  peroxide. 

Peroxide  of  Tin.—  Atom.  Num.  ?3'9—  Symb.  2O+Sn 

Sometimes  called  Stannic  Acid. 

PROPERTIES.  White,  fusible  and  undecomposable  by  heat  ;  insoluble 
in  water  ;  it  has  a  feeble  affinity  for  acids,  and  does  not  unite  with  the 
nitric  at  all  ;  it  unites  with  the  alkalies  forming  soluble  compounds 
with  them,  and  when  fused  with  glass  forms  white  enamel. 

NATIVE  STATE  AND  PREPARATION.  This  oxide  is  found  native  in 
Cornwall,  in  Spain,  and  in  Saxony  ;  it  has  also  been  found  in  Brittany, 
in  France,  in  the  East-Indies,  and  in  South-America.  The  specific 
gravity  of  the  native  oxide  is  7  ;  its  primitive  crystal  is  an  octahedron 
with  a  square  base. 

The  peroxide  of  tin  may  be  prepared  artificially  by  treating  the 
metal  with  nitric  acid.  There  is  a  violent  action,  attended  with  the 
formation  of  nitrate  of  ammonia.  Scarcely  any  of  the  metal  is  dis- 
solved, but  remains  as  a  yellowish  powder,  which  may  be  purified  by 
washing. 

TIN    AND    CHLORINE*. 

Tin  unites  in  two  proportions  with  chlorine  ;  and  the  researches  of 
Dr.  Davy  leave  no  doubt  of  these  compounds  being  analogous  in  com- 
position to  the  oxides  of  tin. 

Protochloride  of  Tin.—  Atom.  Num.  93*35—  Symb.  Cl+Sn. 

A  gray  solid  substance,  of  a  resinous  lustre,  which  fuses  at  a  heat 
below  redness,  and  when  heated  in  chlorine  gas,  is  converted  into  the 
perchloride.  It  is  prepared  either  by  evaporating  the  muriate  of  the 
protoxide  to  dryness  and  fusing  the  residue  in  a  close  vessel,  or  by 
heating  an  amalgam  of  tin  with  calomel. 

Perchloride  of  Tin.—  Atom.  Num.  12S'8—Symb.  2Cl+Sn. 

SYN.     Butter  of  Tin.     Fuming  Liquor  of  Libavius. 

A  colourless  volatile  liquid,  which  emits  copious  white  fumes  when 
exposed  to  the  atmosphere  ;  it  has  a  strong  attraction  for  water,  and 
is  converted  by  that  fluid  into  the  Permuriate  of  Tin. 

This  chloride  may  be  prepared  either  by  heating  metallic  tin  or  the 
protochloride,  in  an  atmosphere  of  chlorine,  or  by  distilling  a  mixture 


UNIVERSITY 


286  TIN. 

of  eight  parts  of  tin  in  powder,  with  twenty-four  of  corrosive  subli- 
mate. 

Both  the  chlorides  of  tin  possess  the  characters  of  an  acid,  and  are 
capable  of  combining  with  chlorine  bases,  though  only  a  few  of  these 
salts  have  been  hitherto  investigated.  They  are  denominated  Chloro- 
Stannatcs  by  Dr.  Thomson.  —See  his  Inorg.  Chem.  ii.  824. 

Tin  also  combines  with  bromine  and  iodine  ;  with  the  former  in  two 
proportions. 


TIN    AND    SULPHUR. 

Protosulplmret  of  Tin.— Atom.  Num.tSQ—Symb.  S-fSn. 

A  brittle  compound  of  a  bluish  gray  colour  and  metallic  lustre  ;  fu- 
sible at  a  red  heat,  and  assuming  a  laminated  structure  in  cooling.  It 
is  best  formed  by  heating  sulphur  with  metallic  tin. 

Bisulphuret  of  Tin.— Atom.  Num.  89-9—  Symb    2S+Sn. 

A  compound  of  a  golden  yellow  colour,  formerly  called  durum 
Musivum,  made  by  heating  a  mixture  of  sulphur  and  peroxide  of  tin 
in  close  vessels. 

By  exposing  a  mixture  of  sulphur  and  protosulphuret  of  tin  to  a  low 
red  heat,  Berzelius  obtained  a  compound  of  one  proportion  of  tin  and 
one  and  a  half  of  sulphur.  If  it  be  really  a  definite  compound,  it 
should  be  termed  a  Sesquisulphuret. 

TIN    AND    THE    METALS. 

Most  of  the  malleable  metals  become  brittle  and  lose  their  ductility 
by  combination  with  tin  ;  and  hence  tin  was  formerly  called  Diabolus 
MetaUorum. 

The  common  tin  plate,  so  extensively  employed  in  the  arts,  may  be 
considered  as  an  alloy  of  tin  and  iron. 

For  forming  this  valuable  article,  the  iron,  .after  being  rolled  into 
thin  sheets,  is  completely  cleansed  and  freed  from  oxide,  by  being 
steeped  in  water  acidulated  with  muriatic  acid.  It  is  afterwards  plung- 
ed into  a  vessel  of  melted  fat  and  oil.  At  the  same  time  also,  the  tin 
is  kept  melted  in  an  oblong  rectangular  vessel ;  and  to  preserve  its  sur- 
face from  oxidation,  a  quantity  of  melted  fat  and  oil  is  kept  floating 
on  it.  The  iron  plates  are  then  immersed  in  the  tin  for  some  time,  and 
when  withdrawn  they  are  found  to  have  a  bright  coating  of  tin.  The 
dipping  is  repeated  twice  or  more  times,  according  to  the  thickness  of 
the  coat  intended  to  be  given,  and  also  to  produce  a  smooth  surface, 
and  between  these  processes  the  tin  is  equalized  with  a  brush. — See 
Bishop  Watson's  Chem.  Essays,  and  Parkes'  account  of  the  Manufacture 
of  Tin  Plate,  Manchester  Memoirs,  iii.  N.  S..  or  Brandes  Jour.  viii. 
141. 

When  tin  plate  is  exposed  to  the  vapour  of  muriatic  acid,  or  if  the 
plate  is  washed  with  almost  any  dilute  acid,  it  assumes  the  appear- 
ance of  what  is  called  Crystallized  or  Watered  Tin.  This  article  is  ex- 
tensively employed  to  cover  ornamental  cabinet  work,  dressing  boxes, 
&c.  and  is  the  Fer  blanc  moire  of  the  French.  The  best  acid  solutions 
for  this  purpose,  are  2  parts  of  nitric  acid,  3  parts  of  muriatic,  and  8 


TIN.  287 

of  water,  or  citric  acid  dissolved  in  a  sufficient  quantity  of  water  — 
The  watered  tin  is  a  true  crystallization  of  the  alloy  ;  and  the  process 
is  much  improved  by  heating  the  plate  in  different  parts  by  means  of  a 
blow-pipe,  or  by  raising  the  temperature  of  the  whole  plate  to  near 
redness,  and  then  pouring  the  cold  acid  mixture  upon  it,  or  plunging 
the  plate  into  the  liquor. — Thenard,  i.  635.  Bmnde's  Jour.  v.  368. 


SALTS    OF    TIN. 

lodate  of  Tin.  —  An  orange  coloured  substance  formed  either  by  the 
direct  combination  of  tin  with  iodine,  or  by  adding  hydriodie  acid  to 
protomuriate  of  tin.  The  proportion  of  its  elements  has  not  been  de- 
termined. 

Protomuriate  of  Tin.—  Atom.  Num.  l\l.3o—  Symb.  (Cl-f-H) 

Aq. 


This  compound,  when  evaporated  out  of  contact  of  air,  is  a  white 
salt  which  may  be  obtained  in  large  oblique  four-sided  prisms,  transpa- 
rent, of  a  silky  lustre,  and  acid  to  the  taste,  and  to  colour  tests. 

The  protomuriate  of  tin  may  be  obtained  by  boiling  one  part  of  tin 
with  two  of  muriatic  acid,  in  a  tubulated  retort.  The  solution  has  al- 
ways an  excess  of  acid,  and  is  perfectly  limpid  and  colourless.  It  has 
a  tendency  to  acquire  an  additional  proportion  of  oxygen,  and  should 
therefore  be  preserved  from  contact  with  the  air.  This  property  of 
absorbing  oxygen  is  so  remarkable,  that  it  may  even  be  applied  to  eudio- 
metrical  purposes.  It  has  also  the  property  of  reducing  to  a  minimum 
of  oxidation,  those  compounds  of  iron,  in  which  the  metal  is  fully 
oxidized  ;  for  example,  it  reduces  the  red  sulphate  to  the  green.  It  is 
a  test  also  of  gold  and  platinum,  and  blackens  the  solution  of  corro- 
sive sublimate.  With  hydros  ulphurets  it  gives  a  black  precipitate.  — 
Henry's  C/tem.  ii.  45. 

REFERENCES.  On  tht  preparation  of  Muriate  o/'jT/.",  see  Berard,  Ann.  de 
Chini.  xviii.  78,  or  Nicholsoifs  Jour.  xxvi.  and  Chaudet,  'Ann.  de  CLim.  et 
de  Phys.  iii.  376. 

The  muriates,  as  well  as  the  oxide  of  tin,  are  poisonous.  —  Christison 
on  Poisons.  367. 

Nitromuriate  of  Tin.  —  The  nitromuriatic  acid  dissolves  tin  abun- 
dantly, and  with  violent  effervescence  arid  so  much  heat  that  it  is  ne- 
cessary to  add  the  metal  slov,  ly  by  successive  portions.  The  solution 
is  apt  to  congeal  into  a  tremulous  gelatinous  mass  ;  and  if  water  be  ad- 
ded, it  is  partly  decomposed,  and  some  oxide  separated. 

This  compound  is  supposed  to  be  a  Permuriate  of  Tin.  It  is  used 
to  heighten  the  colours  of  cochineal,  gum  lac,  and  some  other  red 
tinctures,  from  crimson  to  a  bright  scarlet.  It  is  prepared  by  artists 
with  that  dilute  nitric  acid  called  single  aqua-fortis,  to  each  pound  of 
which,  are  added  from  one  to  two  ounces  of  muriate  of  soda  or  am- 
monia. This  compound  is  capable  of  taking  up  about  an  eighth  of  its 
weight  of  tin.  —  Henry.  Thenard,  iii.  358. 

Nitrate  of  Tin.  —  This  may  be  formed  by  treating  the  metal  with  di- 
lute nitric  acid  ;  a  yellow  solution,  which  will  not  crystallize,  is  ob- 
tained ;  when  exposed  to  the  air  it  absorbs  oxygen,  and  peroxide  of  tin 


288  CADMIUM. 

precipitates  ;  if  evaporated,  the  peroxide  falls,  and  a  portion  of  ni- 
trate of  ammonia  is  formed,  part  of  the  water  as  well  as  of  the  acid  be- 
ing decomposed. 

Sulphate  of  Tin. — When  tin  is  boiled  in  sulphuric  acid,  a  solution  is 
obtained  which  deposits  white  acicular  crystals.  A  protosulphate  of 
tin  is  also  precipitated  by  pouring  sulphuric  acid  into  protomuriate  of 
tin. 

TESTS  OF  THE  SALTS  OF  TIN.  These  salts  are  mostly  soluble  in  wa- 
ter, and  are  precipitated  of  an  orange  colour  by  hydriodic  acid,  and  by 
hydrosulphuret  ef  ammonia,  provided  no  excess  of  acid  be  present. 
Solutions  of  chloride  of  gold  and  of  corrosive  sublimate,  produce  pur- 
ple and  black  precipitates  in  the  salts  containing  the  protoxide,  but 
none  in  those  containing  the  peroxide.  Ferrocyanate  of  patassa  pro- 
duces a  white  precipitate  in  solution  of  muriate  of  tin. 

SECTION  XVIIL 

CADMIUM. 

Atom.  Num.  55-3— Symb.  C<\.—  Sp.  gr.  8-604.] 

This  metal  was  discovered  in  1817,  by  Professor  Stromeyer,  of 
Gottingen,  in  an  oxide  of  zinc,  which  had  been  prepared  for  medical 
use  from  an  ore  of  zinc  brought  from  Silesia.  It  has  since  been  dis- 
covered by  Dr.  Clarke  in  the  zinc  ores  of  Derbyshire,  and  in  the  com- 
mon zinc  of  commerce,  and  by  Mr.  Herapath  in  the  zinc  works  near 
Bristol,  England. 

PROPERTIES.  This  metal  is  nearly  as  white  as  tin,  but  is  somewhat 
harder  and  more  tenacious  ;  it  is  very  ductile  and  malleable,  and  sus- 
ceptible of  a  high  polish  ;  its  specific  gravity  is  8-604  before  being 
hammered,  and  8-694  afterwards  ;  it  melts  at  about  the  same  tempera- 
ture as  tin,  and  is  nearly  as  volatile  as  mercury,  condensing  into  glo- 
bules which  have  a  metallic  lustre  ;  its  vapour  has  no  odour. 

EXTRACTION.  The  process  by  which  Stromeyer  separates  cadmium 
from  zinc  or  other  metals  is  the  following.  The  ore  of  cadmium  is 
dissolved  in  dilute  sulphuric  or  muriatic  acid,  and  after  adding  a  por- 
tion of  free  acid,  a  cunent  of  sulphuretted  hydrogen  gas  is  transmit- 
ted through  the  liquid,  by  means  of  which  the  cadmium  is  precipitated 
as  sulphuret,  while  the  zinc  continues  in  solution.  The  sulphuret  of 
cadmium  is  then  decomposed  by  nitric  acid,  and  the  solution  evapo- 
rated to  dryness.  The  dry  nitrate  of  cadmium  is  dissolved  in  water, 
and  an  excess  of  carbonate  of  ammonia  added.  The  white  carbonate 
of  cadmium  subsides,  which,  when  heated  to  redness,  yields  a  pure 
oxide.  By  mixing  this  oxide  with  charcoal,  and  exposing  the  mixture 
to  a  red  heat,  metallic  cadmium  is  sublimed. 

A  very  elegant  process  for  separating  zinc  from  cadmium  was  pro- 
posed by  Dr.  Wollaston.  The  solution  of  the  mixed  metals  is  put  into 
a  platinum  capsule,  and  a  piece  of  metallic  zinc  is  placed  in  it.  If 
cadmium  is  present,  it  is  reduced,  and  adheres  so  tenaciously  to  the 
capsule,  that  it  may  be  washed  with  water  without  danger  of  being 
lost  It  may  then  be  dissolved  either  by  nitric  or  dilute  muriatic  acid. 
— Turner. 


CADMIUM.  289 

REFERENCES.  Stromeyer  on  Cadmium,  Ann.  of  Phil  xiii.  103,  xiv.  279. 
Dr.  E.  I).  Clarke  on  the  discovery  of  this  meted  in  the  Derbyshire  ores  of  Zinc, 
Ann.  of  Phil.  xv.  272,  and\\s..  1^3.  Kerapath  on  Cadmium,  and  the  sources 
of  procuring  it  in  quantity,  Ann.  of  Phil.  xix.  435. 

CADMIUM    AND    OXYGEN. 

Oxide  of  Cadmium. — Atom.  Num.  63%8 — Symb.  O+Cd. 

PROPERTIES.  The  oxide  of  cadmium  is  of  an  orange  yellow  colour, 
and  fixed  in  the  fire  ;  it  is  insoluble  in  water,  and  does  not  change  the 
colour  of  violets,  but  is  a  powerful  salifiable  base,  forming  neutral  salts 
with  acids  ;  it  is  precipitated  as  a  white  hydrate  by  pure  ammonia,  but 
is  redissolved  by  excess  of  that  alkali ;  it  is  precipitated  permanently 
by  pure  potassa  as  a  hydrate,  and  by  all  the  alkaline  carbonates,  as 
carbonate  of  cadmium. 

The  oxide  of  cadmium  may  be  obtained  by  heating  the  metal  in  open 
air,  and  also  by  igniting  the  carbonate, 

Chloride  of  Cadmium,  crystallizes  in  small  rectangular  prisms,  per- 
fectly transparent,  which  effervesce  when  heated,  and  are  very  soluble. 
At  high  temperatures  it  sublimes  in  small  micaceous  plates. 

Iodide  of  Cadmium  forms  large  and  beautiful  hexahedral  tables  of  a 
metallic  or  pearly  lustre.  At  a  high  temperature  the  iodine  escapes. 

Sulphuret  of  Cadmium  occurs  native  in  some  kinds  of  zinc  blende, 
and  is  easily  procured  by  the  action  of  sulphuretted  hydrogen  on  a  salt 
of  cadmium.  It  has  a  yellowish  orange  colour,  and  is  distinguished 
from  the  sulphuret  of  arsenic  by  being  insoluble  in  pure  potassa,  and 
by  sustaining  a  white  heat  without  subliming. 

Phosphuret  of  Cadmium  has  a  gray  colour  and  feeble  metallic  lustre, 
is  brittle  and  very  little  fusible. 

CADMIUM  AND  THE  METALS. 

Cadmium  unites  readily  with  other  metals,  and  forms  brittle  alloys. 
When  these  alloys  are  exposed  to  a  very  high  temperature,  the  cadmi- 
um is  volatilized.  It  also  unites  with  mercury  and  forms  an  amalgam 
which  has  a  silvery  appearance,  and  crystallizes  in  octahedrons. — Ber~ 
zelius. 

SALTS    OP    CADMIUM. 

Nitrate  of  Cadmium.— Atom.   Num.   153-S— Symb.  (5O+NI 
+(O+Cd.)+4Aq. 

This  salt  crystallizes  in  needles  or  prisms,  which  are  deliquescent. 

Sulphate  of  Cadmium. — Atom.  Num.  139-8— %M&.  (3O+S) 
+{0+Cd.)-M  Aq. 

Crystallizes  in  large  rectangular  prisms,  resembling  sulphate  of  zinc, 
which  are  soluble  in  water,  effloresce  hi  the  air,  and  -at  a  gentle  heat, 
^ose  their  water  of  crystallization. 


290  NICKEL. 

Phosphate  of  Cadmium. — Atom.   Num.   108*5 — Syrnb. 
(2JO+P)+(0+Cd.)+l  Aq. 

A  pulverulent  and  tasteless  salt ;  insoluble  in  water,  and  formed  by 
mixing  solutions  of  nitrate  of  cadmium  and  phosphate  of  soda. 

Carbonate  of  Cadmium.— Atom.  Num.  Si'S—Symb.  (2O+C) 
+(0+Cd.) 

A  white  tasteless  powder,  having  a  certain  resemblance  in  colour  to 
white  lead  ;  it  is  insoluble  in  water,  and  readily  decomposable  by  heat ; 
it  is  destitute  of  combined  water,  but  when  dried  in  the  open  air,  re- 
tains the  fifth  part  of  an  atom  of  water,  no  doubt  hygrometrically  uni- 
ted to  the  salt. — Thomson. 

REFERENCES.  I 'or  further  information  concerning  the  Salts  of  Cadmium, 
see  the  Papers  of  Strumeyer  abuve  quoted,  and  Thomsoifs  First  Prin.  u. 
360. 

SECTION  XIX, 

NICKEL. 
?  Atom.  Num.  29-5-—  Symb.  Tti.—Sp.  gr.  8  279. 

Discovered  by  Cronstedt,  in  1751,  in  the  Copper  Nickel  of  West 
phalia, 

PROPERTIES.  Nickel  has  a  white  colour,  intermediate  between  thosv% 
of  silver  and  iron  ;  is  susceptible  of  a  fine  polish  ;  is  both  ductile 
and  malleable  ;  its  specific  gravity  after  fusion  is^  about  8-279,  and  is 
increased  to  near  9-0  by  hammering  ;  it  is  attracted  by  the  magnetr 
and  like  iron  and  cobalt  may  be  rendered  magnetic;  is  exceedingly 
infusible,  even  more  so  than  pure  iron  ;  suffers  no  change  at  cornmoR 
temperatures  by  exposure  to  air  and  moisture,  but  absorbs  oxygen  at 
a  red  heat,  though  not  rapidly,  and  is  partially  oxidized. 

EXTRACTION.  The  principal  source  from  which  nickel  is  obtained, 
is  a  substance  called  Speiss,  an  artificial  arseniuret  of  nickel,  which  re- 
mains at  the  bottom  of  the  crucibles  in  which  zaffre  is  prepared.  Va- 
rious processes  have  been  proposed  for  extracting  the  metal  from  this 
compound,  of  which  that  of  Dr.  Thomson  is  the  most  simple  and  per- 
haps as  successful  as  any.  It  consists  in  reducing  the  speiss  to  pow- 
der and  digesting  it  in  a  mixture  of  sulphuric  and  nitric  acids.  The 
crystals  obtained  by  evaporation  are  free  from  arsenic,  iron,  bismuth 
and  antimony,  but  are  contaminated  with  a  little  cobalt  and  copper. 
The  copper  is  to  be  precipitated  from  a  watery  solution  of  these 
crystals  by  a  current  of  sulphuretted  hydrogen,  and  the  oxide  of  nick- 
el when  washed,  but  still  moist,  is  to  be  exposed  to  chlorine  gas, 
which  dissolves  the  oxide  of  nickel,  leaving  that  of  cobalt  untouched, 
The  muriate  of  nickel  is  easily  convened  into  sulphate,  by  the  addi- 
tion of  a  due  proportion  of  sulphuric  acid,  and  the  sulphate,  by  one  or 
more  crystallizations,  is  obtained  pure*  From  this  salt,  dissolved  in 


NICKEL.  291 

water,  carbonate  of  nickel  is  precipitated  by  carbonate  of  soda,  or 
potassa,  and  after  being  well  edulcorated,  is  to  be  dried  and  cal- 
cined. 

Metallic  nickel  may  be  prepared  either  by  heating  the  oxalate  in 
close  vessels,  or  by  the  combined  action  of  heat  and  charcoal,  or  hydro- 
gen, on  the  oxide  of  nickel. 

REFERENCES.  Thomson,  in  Phil.  Mag.  and  Ann.  ii.  151.  Robiquet,  in 
Ann.  de  Chini.  Ixix.  Mill,  in  Ann.  of  Phil.  xix.  201.  Laugier,  in  Ann.  de 
Chim.  et  de  Phys.  ix. ;  and  Berliner,  samewor/c,  xxv.  and  xxxiii.  Berzelius, 
Traitede  Chim.  iii.  210.  Hisiiiger  and  Murray's  experiments  on  jNiccolane- 
?tw,  Ann.  of  Phil.  i.  116.  Dr.  Clarke's  method  of  obtaining  gure  Nickel  by 
the  compound  blowpipe,  same  work,  xiv.  142. 

NICKEL    AND    OXYGEN. 

Nickel  seems  to  be  susceptible  of  only  two  states  of  oxidation  ;  but 
Berzelius  decribes  three  oxides. 

Protoxide  of  Nickel. — Atom.  Num.  37*5 — Symb.  O+Ni. 

PROPERTIES.  This  is  of  an  ash-gray  colour,  but  when  heated  to 
whiteness,  of  a  dull  olive-green  ;  it  is  not  attracted  by  the  magnet ;  is 
a  strong  salifiable  base,  and  nearly  all  the  salts  have  a  green  tint ;  is 
precipitated  as  a  hydrate,  of  a  pale  green  colour,  by  the  pure  alkalies, 
but  is  redissolved  by  excess  of  ammonia. 

It  is  formed  by  heating  the  carbonate,  oxalate  or  nitrate,  to  redness 
in  an  open  vessel. 

Peroxide  of  Nickel— Atom.  Num.  41'5—Symb.  1  JO+Ni. 

The  peroxide  of  nickel  is  of  a  black  colour,  and  is  formed  by  trans- 
mitting chlorine  gas  through  water,  in  which  the  hydrate  of  the  pro- 
toxide is  suspended.  It  does  not  unite  with  acids  ;  is  decomposed  by 
a  red  heat,  and  with  hot  muriatic  acid  forms  a  proto-muriate,  with  dis- 
engagement of  chlorine  gas. 

Nickel  combines  with  chlorine,  iodine,  phosphorus,  sulphur  and  car- 
bon ;  but  these  compounds  do  not  possess  any  very  striking  properties. 
According  to  Mr.  Ross,  the  carburet  of  nickel  is  apt  to  form  when  nick- 
el is  reduced  from  its  salts  by  carbonaceous  matter.  It  resembles 
iodine,  or  micaceous  iron  ore. — Ann.  of  Phil,  xviii.  62,  149  ;  xix.  201. 

NICKEL    AND    THE    METALS. 

Nickel  may  be  alloyed  with  most  of  the  metals,  but  few  of  them  are 
peculiarly  interesting.  An  alloy  of  iron  and  nickel  has  been  found  in 
all  the  meteoric  stones  that  have  been  hitherto  analyzed,  however  re- 
mote from  each  other  the  parts  of  the  world  in  which  they  have  fallen. 
In  these  it  forms  from  I  1-2  to  17  per  cent,  of  their  weight. — It  enters, 
also,  into  the  composition  of  the  masses  of  native  iron  discovered  in  Si- 
beria and  South-America  ;  and  was  found  by  Mr.  Brande  to  the  ex- 
tent of  3  per  cent,  in  native  iron  brought  from  the  arctic  regions. — 
Brande  s  Jour.  vi.  369,  and  ix.  323. 


292  NICKEL. 

Meteoric  iron  has  been  imitated  by  fusing  iron  with  nickel.  The 
alloy  of  90  iron  with  10  nickel,  is  of  a  whitish  yellow  cast,  and  not  so 
malleable  as  pure  iron.  The  alloy  with  3  per  cent,  of  nickel,  is  per* 
fectly  malleable,  and  whiter  than  iron.  These  alloys  are  less  disposed 
to  rust  than  pure  iron  ;  but  nickel  alloyed  with  steel  increases  the  ten- 
dency  to  rust.  —  Stodart  and  Faraday,  in  Brande's  Jour.  ix.  324. 

An  alloy  of  copper  and  nickel  occurs  in  nature,  and  is  known  by  the 
name  of  Copper-nickel.  It  is  of  a  copper  colour  and  in  addition  to  its 
chief  ingredients  contains  sulphur,  iron  and  cobalt. 

But  the  most  important  of  the  alloys  of  nickel,  is  the  Tutenag  or 
Packfong  of  the  Chinese.  It  is  a  compound  of  copper,  tin,  zinc  and 
nickel.  It  is  malleable,  and  is  employed  in  the  fabrication  of  various 
utensils.  This  alloy  is  now  successfully  manufactured  at  Vienna.  — 
See  an  account  of  the  manufacture  of  Pachfong,  in  Brewsters  Edin.  Jour* 
of  Science,  N.  S.  i.  167. 

SALTS    OF    NICKEL. 

Nitrate  of  Nickel.—  Atom.  Num.  I3fr5—Symb.  (5O+N) 


This  salt  crystallizes  in  four-sided  oblique  prisms  ;  has  a  green  co- 
lour, and  does  not  undergo  any  change  by  exposure  to  the  air.  —  Thorn' 
son's  First  Prin.  ii.  333. 

Sulphate  of  Nickel.—  Atom.  Num.  140-5—  Symb.  (30+8)4- 
(0+Ni.)+7  Aq. 

This  salt  has  a  beautiful  grass-green  colour,  and  crystallizes  in  rhom* 
bic  and  in  square  prisms.  —  Thomson. 

Phosphateof  Nickel—  Atom.  Num.  WQ'2—Symb.  (2|O+P) 
+  (0+Ni.)+3Aq. 

A  powder  of  a  light  pea-green  colour,  tasteless  and  insoluble  in  wa* 
ter.  It  is  obtained  by  mixing  together  solutions  of  sulphate  of  nickel 
and  phosphate  of  soda,  in  the  atomic  proportions. 

Carbonate  of  Nickel  —  A  light  green  tasteless  powder,  insoluble  in 
water,  but  dissolving  with  effervescence  in  acids  ;  formed  by  precipita* 
ting  a  solution  of  sulphate  of  nickel  by  carbonate  of  soda. 

REFERENCES.  Thomson  on  the  Salts  of  Nickel,  First  Prin.  ii.  833,  and 
Inorg.  Chem.  ii.  596. 

TESTS  OF  THE  SALTS  OF  NICKEL.  The  solution  of  these  salts  has 
a  fine  green  colour,  and  affords  a  green  precipitate  with  ammonia,  so* 
luble  in  excess  of  that  alkali,  when  it  assumes  a  blue  colour.  Hydrio* 
date  of  potassa  produces  a  very  characteristic  yellowish  green  precipi- 
tate ;  and  the  ferrocyanate  of  potassa,  one  of  a  pale  gray  or  greenish 
white. 


COBALT.  293 

SECTION  XX. 

COBALT. 

Atom.  JVTttw.  29.5—  Symb.  Co.—  Sp.  gr.  8.538. 

This  metal  appears  to  have  been  discovered  by  Brandt.  It  is  met 
with  in  the  earth,  chiefly  in  combination  with  arsenic,  known  by  the 
name  of  Arsenical  Cobalt.  It  is  also,  according  to  Stromeyer,  a  con- 
stant ingredient  in  meteoric  iron. 

PROPERTIES.  Cobalt  is  solid,  hard  and  brittle  ;  of  a  reddish  gray 
colour,  and  weak  metallic  lustre  ;  it  fuses  at  about  130°  of  Wedge- 
wood,  and  when  slowly  cooled  it  crystallizes  ;  is  attracted  by  the  mag- 
net, and  is  susceptible  of  being  rendered  permanently  magnetic  ;  ab- 
sorbs oxygen  when  heated  in  open  vessels ;  is  readily  oxidized  by 
nitric  acid,  but  is  with  difficulty  attacked  by  sulphuric  or  muriatic 
acid. 

NATIVE  STATE  AND  EXTRACTION.  Cobalt  is  found  in  nature  in  the 
form  of  oxide,  of  sulphate,  ofarseniate,  and  in  combination  with  many 
combustibles,  especially  with  sulphur  and  arsenic.  From  the  oxide, 
metallic  cobalt  may  be  obtained  by  heating  it  with  charcoal,  by  passing 
over  it  a  stream  of  hydrogen  gas,  or  by  heating  strongly  the  oxalate  of 
cobalt  in  close  vessels. 

REFERENCES.  Thomson,  in  Ann.  of  Phil,  xvii.  250.  For  Trommsdorfs 
process  for  obtaining  pure  Cobalt^  see  Repert.  of  Arts,  %d  ser.  ii.  453,  ir.  126, 
andvm.  154.  Laugier^s  process  for  separating  Cobalt  and  Nickel^is  describ- 
ed in  Ann.  of  Phil.  xiii.  38,  and  in  Branded  Jour.  ix.  181. 

COBALT    AND    OXYGEN. 

Chemists  are  acquainted  with  two  compounds  of  oxygen  and  co  • 
bait. 

Protoxide  of  Cobalt. — Atom.  Num.  37'5 — Symb.  O+Co. 

This  oxide  is  of  an  ash-gray  colour,  and  is  the  basis  of  the  salts  of 
cobalt,  most  of  which  are  of  a  pink  blue  ;  it  absorbs  oxygen  when 
heated  in  open  vessels,  and  is  converted  into  the  peroxide.  It  may  be 
prepared  by  decomposing  carbonate  of  cobalt  by  heat,  in  a  close  vessel ; 
and  may  be  easily  recognized  by  giving  a  blue  tint  to  borax  when  melt- 
ed with  it. 

The  substance  known  in  the  arts  by  the  name  of  Zaffre,  is  an  im- 
pure oxide  of  cobalt,  prepared  by  exposing  the  native  arseniuret  of  co 
bait,  in  a  reverberatory  furnace,  to  the  united  action  of  heat  and  air. 
On  heating  this  substance  with  a  mixture  of  sand  and  potassa,  a  beau- 
tiful blue  coloured  glass  is  obtained,  which  when  reduced  to  powder, 
is  known  by  the  name  of  Smalt.  In  this  form  it  is  much  employed  in 
the  arts  for  communicating  a  similar  colour  to  glass,  earthen- ware,  and 
porcelain.  For  details  concerning  the  preparation  of  this  substance  and 
its  employment  in  the  arts,  see  Aikins  Chem.  Diet,  and  Parkcs*  Chem. 
Essay's,  iii.  338. 


294  COBALT. 


Peroxide  of  Cobalt.— Atom.  Num.  4.1-5— Symb.  If  0+Co. 

This  oxide  is  of  a  black  colour,  and  is  easily  formed  from  the  protox- 
ide in  the  way  already  mentioned.  It  does  not  unite  with  acids  ;  and 
when  digested  in  muriatic  acid,  the  protomuriate  of  cobalt  is  generated 
with  disengagement  of  chlorine.  When  strongly  heated  in  close  ves- 
sels, it  gives  off  oxygen,  and  is  converted  into  the  protoxide. 

This  compound  appears  to  form  salts  with  bases,  especially  ammo- 
nia. Gmelin  calls  it  Cobaltic  Acid. — Ann.  of  Phil.  2d  scr.  ix.  69. 


COBALT    AND    CHLORINE. 

Cobalt  takes  fire  when  introduced  in  a  finely  divided  state,  into  chlo- 
rine gas  ;  but  the  compound  has  not  been  examined. 

COBALT    AND    SULPHUR. 

According  to  Berzelius,  cobalt  combines  in  several  proportions  with 
sulphur,  but  the  compounds  do  not  appear  to  possess  any  peculiarly  in- 
teresting properties. — Berzelius ,  Traite  de  Chim.  iii.  232. 

SALTS  OF  COBALT. 

Muriate  of  Cobalt. — A  deliquescent  salt,  of  a  blue-green  colour  ; 
when  a  little  diluted  the  solution  becomes  pink  ;  the  pale  pink  solution, 
when  written  with,  is  scarcely  visible  ;  but  if  gently  heated,  the  writ- 
ing appears  brilliant  and  green,  which  soon  vanishes,  as  the  paper 
cools.  This  solution  has  been  termed  HeitoCs  Sympathetic  Ink. 

This  salt  may  be  prepared  by  digesting  either  oxide  in  muriatic  acid. 
The  sympathetic  solution  may  be  obtained  by  digesting  one  part  of 
cobalt  or  of  zaffre  in  a  sand  heat  for  some  hours,  with  four  parts  of  ni- 
tric acid.  To  the  solution  add  one  part  of  muriate  of  soda  ;  and  di- 
lute with  four  parts  of  water.  Characters  written  with  this  solution 
are  illegible  when  cold  ;  but  when  a  gentle  heat  is  applied  they  assume 
a  beautiful  blue  or  green  colour. 

Nitrate  of  Cobalt,  occurs  in  crystals,  which  have  an  acrid  and  bitter 
taste,  redden  vegetable  blues,  and  deliquesce  rapidly  when  exposed  to 
the  air.  It  is  easily  obtained  by  dissolving  cobalt,  or  its  oxide,  in  nitric 
acid. 

Sulphate  of  Cobalt. — This  salt  has  a  deep  red  colour,  and  crystallizes 
in  rhombic  prisms,  similar  to  the  form  of  sulphate  of  iron.  There  is 
also  a  Bisulphate* 

Phosphate  of  Cobalt,  is  formed  by  dissolving  the  carbonate  in  phos- 
phoric acid  and  adding  alcohol,  or  by  mixing  muriate  of  cobalt  and 
phosphate  of  soda.  A  lilac  piecipitate  in  the  last  case  falls,  which  if 
mixed  with  eight  parts  of  fresh  precipitated  alumina  and  dried,  forms, 
according  to  Thenard,  a  blue  pigment  that  may  be  substituted  for 
Ultra-marine,  and  is  known  by  the  name  of  Thenard' s  Blue,  or  Cobalt 
Blue.  For  a  full  description  of  the  process,  see  Brandcs  Jour.  xv.  381; 
Thenard' s  Traite  de  Chim.  iii.  146  ;  and  Franklin  Jour.  ii.  3. 


COBALT.  295 

Carbonate  of  Cobalt — a  light  powder,  of  a  pink  colour,  tasteless,  in  - 
soluble  in  water,  and  not  altered  by  exposure  to  the  air.  It  does  not 
alter  vegetable  blues,  but  dissolves  in  acids  with  a  strong  effervescence 
It  is  formed  by  decomposing  the  nitrate,  muriate  or  sulphate  of  cobalt 
with  carbonate  of  potassa,  and  washing  and  drying  the  precipitate. 

REFERENCES.     Thomson  on  the  Salts  of  Cobalt,   First  Princip.  ii.  341. 

TESTS  OF  THE  SALTS  OF  COBALT.  All  the  salts  of  cobalt  contain  the 
protoxide  ;  oxalic  acid  throws  down  from  their  solutions  a  rose-colour- 
ed precipitate  ;  ferrocyanate  of  potassa  one  of  a  grass  green  colour  ; 
solution  of  borax  a  pink  compound  ;  and  hydrosulphuret  of  ammonia 
a  black  hydrosulphuret  of  cobalt. — Henry. 


296  ARSENIC. 


CLASS  V. 

METALS,  WHICH  DO  NOT  DECOMPOSE  WATER  AT  ANY  TEM- 
PERATURE, AND  THE  OXIDES  OP  WHICH  ARE  NOT  REDUC- 
ED TO  THE  METALLIC  STATE  BY  THE  SOLE  ACTION  OF 
HEAT. 


ORDER  I. 

METALS,    WHICH,    WHEN   COMBINED   WITH   OXYGEN,    FORM   ACIDS. 

SECTION  XXL 

ARSENIC. 
Atom.  Num.  37-7-— Symb.  As.— Sp.  gr  5  70. 

This  metal  was  known  to  the  ancients,  its  combination  with  sulphur 
being  noticed  by  Dioscorides,  under  the  name  of  Sfindarac.  Its  peculiar 
nature,  however,  was  first  demonstrated  by  Brandt,  in  1733. 

PROPERTIES.  An  exceedingly  brittle  metal,  of  a  strong  metallic  lus- 
tre, and  steel  gray  colour  ;  its  structure  is  crystalline  ;  at  3563  F.  it 
volatilizes  without  being  fused,  and  in  close  vessels  may  be  collected 
unchanged  ;  but,  when  thrown  on  a  red  hot  iron,  it  burns  with  a  blue 
flame  and  a  white  smoke,  and  a  strong  smell  of  garlic  is  perceived, 
which  belongs  only  to  the  metal  and  not  to  its  oxides  ;  it  is  speedily 
tarnished  by  exposure  to  air  and  converted  into  a  black  powder,  which 
is  a  mixture  of  the  metal  and  oxide. 

Arsenic  decomposes  many  of  the  Salts. — The  nitrates  detonate  with 
arsenic,  convert  it  into  arsenic  acid,  and  this  combining  with  the  base 
of  the  nitrate,  forms  an  arseniate  that  remains  at  the  bottom  of  the 
vessel. 

If  three  parts  of  chlorate  of  potassa  be  mixed  with  one  part  of  arsen- 
ic in  fine  powder,  which  must  be  done  with  great  caution  and  with  a 
light  hand,  a  small  quantity  of  this  mixture,  placed  on  an  anvil,  and 
struck  with  a  hammer,  will  explode  with  flame  and  a  considerable  re- 
port ;  if  touched  with  fire,  it  will  burn  with  considerable  rapidity  ;  and 
if  thrown  into  concentrated  sulphuric  acid,  at  the  moment  of  contact 
a  flame  rises  into  the  air  like  a  flash  of  lightning,  which  is  so  bright  a£ 
to  dazzle  the  eye. — Ures  C/iem.  Diet. 

NATIVE  STATE  '  AND  PREPARATION.  Metallic  arsenic  sometimes  oc- 
curs native,  but  more  frequently  it  is  found  in  combination  with  other 
metals,  and  especially  with  cobalt  and  iron.  From  the  oxide  obtained 


ARSENIC.  297 


by  roasting  these  ores,  the  pure  metal  may  be  procured  by  mixing  it 
with  oil  and  subliming  at  a  low  red  heat  in  a  clean  Florence  flask,  or 
by  mixing  it  with  about  twice  its  weight  of  black  flux,  [prepared  by 
detonating,  in  a  crucible,  one  part  of  nitre  with  two  of  crystals  of  tar- 
tar,] and  exposing  the  mixture  to  a  red  heat,  in  an  Hessian  crucible, 
over  which  is  luted  an  empty  crucible  for  receiving  the  metal. 

ARSENIC    AND    OXYGEN. 

Chemists  are  acquainted  with  two  compounds  of  these  substances, 
and  as  they  both  possess  acid  properties,  the  terms  Arsenious  and  Arsen- 
ic acid  have  been  properly  applied  to  them.  There  is,  however, 
some  difference  of  opinion  concerning  their  composition.  I  shall 
adopt  the  views  of  Berzelius  with  regard  to  them,  as  probably,  the 
most  correct. 

Arsenius  Acid. — Atom.  Num.  49'7—Symb.  1£  O+As. 

SYN.      White  Oxide  of  Arsenic.     White  Arsenic. 

PROPERTIES.  A  semi-transparent,  white  and  brittle  substance,  of  a 
sweetish  taste  ;  its  specific  gravity  is  3-7  ;  is  volatilized  at  380°  F. 
yielding  vapours,  which  do  not  possess  the  odour  of  garlic,  and  which 
condense  unchanged  on  cold  surfaces  ;  but  if  suddenly  heated  it  runs 
into  a  transparent  brittle  glass ;  it  is  sparingly  soluble  in  water,  and 
more  so  in  hot  than  in  cold  ;  it  reddens  vegetable  blue  colours,  and 
combines  with  salifiable  bases  forming  salts,  which  are  termed  tfrse- 
nites. 

PREPARATION.  This  compound  is  always  generated  when  metallic 
arsenic  is  heated  in  open  vessels,  and  it  may  also  be  prepared  by  di- 
gesting the  metal  in  dilute  nitric  acid. 

ACTION  ON  THE  ANIMAL  ECONOMY. — Arsenious  acid  acts  as  a  poison 
not  only  when  taken  into  the  stomach,  but  when  applied  to  a  wound, 
or  when  its  vapour  is  inspired.  It  is  the  prevailing  opinion  of  writers 
on  this  subject,  that  it  produces  its  deleterious  effects  more  from  its 
constitutional  operation  than  trom  the  local  inflammation  which  it  ex- 
cites. Inflammation,  more  or  less  manifest,  is  certainly  often  present, 
but  frequently  in  fatal  cases  it  is  not  very  striking,  and  it  is  difficult  to 
believe  that  this  and  its  consequences  can  be  the  cause  of  the  rapid  dis- 
solution so  generally  noticed  from  the  exhibition  of  arsenic. 

Toxicologists  are  somewhat  divided  as  to  the  organ  or  part  which  is 
affected.  The  opinion  of  some  is,  that  the  action  "  is  a  consequence 
of  the  poison  entering  the  blood,  and  so  passing  to  the  remote  organs 
acted  on,"  while  others  consider  that  "the  organ  which  is  remotely 
affected  sympathizes,  through  the  medium  of  the  nerves,  with  the  im- 
pression made  on  the  organ  which  is  affected  primarily." 

The  symptoms  vary  with  the  quantity  taken  and  the  constitution  of 
the  sufferer.  The  earliest  and  most  common  are  pain  and  vomiting  ; 
yet  there  are  exceptions  even  'to  these.  In  cases  rapidly  fatal,  extreme 
faintness,  cold  sweats,  oppression  and  slight  convulsions  are  seen.  If 
life  be  prolonged  beyond  twenty-four  hours,  the  vomiting  an.d  retching 
are  often  succeeded  by  diarrho3a,  burning  heat  and  extreme  pain  in  the 
stomach  and  intestines— the  urinary  passages  are  in  many  cases  affect- 
ed— the  pulse  is  very  small — the  countenance  extremely  anxious  and 
the  skin  livid,  or  sometimes  affected  with  eruptions.  In  those  who 


298  ARSENIC. 

survive,  nervous  diseases  resembling  convulsions,  palsy  or  epilepsy  are 
noticed  for  a  length  of  time. 

These  are  the  leading  symptoms  — for  their  variations  in  different 
eases,  see  Christison  on  Poisons,  214  to  229. 

TESTS.  If  the  poison  be  found  in  a  solid  state,  it  should  be  slowly 
dried  on  a  filter.  It  must  then  be  mixed  with  two  parts  or  more  of 
freshly  ignited  charcoal,  and  the  whole  put  into  a  small  glass  tube, 
about  two  inches  long,  and  blown  with  a  small  bulb  at  the  closed  end. 
Apply  gentle  heat  with  the  spirit  lamp,  so  that  the  contained  moisture 
may  be  driven  off,  and  for  this  purpose,  the  upper  part  of  the  material 
may  be  first  heated.  Then  apply  the  flame  to  the  bottom  of  the  tube, 
and  in  a  short  time  a  bright  metallic  crust,  resembling  polished  steel, 
but  darker  in  colour,  will  be  formed  on  the  inside.  This  is  metallic 
arsenic,  and  the  test  is/ called  the  reduction  of  the  metal.  When  heat 
is  cautiously  applied  to  this  crust,  the  metal  rises  in  vapour,  and  the 
alliaceous  odour  will  be  perceived.  2.  If  the  suspected  substance  be 
in  a  fluid  state,  after  adding  as  much  distilled  water  as  may  be  deemed 
necessary,  a  stream  of  Sulphuretted  Hydrogen  Gas  should  be  passed 
into  a  portion  of  it.  The  solution,  if  arsenical,  will  assume  a  bright 
lemon  yellow  colour,  and  in  some  cases  a  yellow  precipitate  will  be 
thrown  down,  being  the  Sulphuret  of  Arsenic.  On  account  of  the 
probability  of  the  suspected  substance  containing  an  alkali,  (in  which 
the  sulphuret  of  arsenic  is  soluble,)  it  is  advisable,  previous  to  the 
above  experiment,  to  add  a  little  dilute  acetic  acid. 

The  sulphuret  thus  formed  may  be  collected,  dried  and  mixed  with 
the  black  flux,  and  placed  in  a  tube  as  above.  On  applying  heat,  the 
polished  crust  of  metallic  arsenic  is  formed. 

To  another  portion,  a  solution  of  nitrate  of  silver  may  be  added  as 
long  as  a  white  precipitate  falls  down,  and  after  its  subsidence,  drop  in 
ammonia  ;  if  arsenic  be  present,  a  beautiful  yellow  precipitate  will  be 
produced,  being  JJrsenite  of  Silver.  This  is  a  modification  of  the  well 
known  test  of  Dr.  Marcet,  and  proposed  by  Dr.  Forbes,  professor  of 
chemistry  at  Aberdeen,  to  obviate  some  of  the  objections  made  to  it. 

To  a  third  portion,  the  ammoniaco-sulphate  of  copper,  in  solution, 
is  added,  when  a  precipitate  of  an  apple  or  grass  green  colour  is  per- 
ceived, being  the  drscnite  of  Copper. 

When  these  results  are  obtained  from  any  suspected  substance,  we 
need  not  hesitate  in  pronouncing  it  arsenic.  No  other  presents  the 
four  characteristic  effects  now  described,  and  it  should  be  remembered 
that  it  is  their  combination  that  renders  the  proof  so  unequivocal.  The 
reduction  is  the  most  satisfactory  and  decisive,  but  even  here,  the  metal 
should  be  re-oxidized,  dissolved  in  water,  and  the  liquid  tests  applied, 
in  order  to  meet  every  possible  objection. 

Sometimes  the  presence  of  organic  matters  interferes  with  the  pro- 
cesses just  mentioned.  Their  removal  may  often  be  sufficiently  effect- 
ed by  adding  acetic  acid  to  the  solution  and  separating  the  coagulated 
substances  by  filtration  ;  but  a  more  complete  separation  may  be  pro- 
duced by  evaporating  the  solution  at  a  moderate  heat  to  dryness,  re- 
dissolving  anew  by  boiling  successive  portions  of  distilled  water  on  the 
residue,  and  then  filtering  the  solution  after  it  has  cooled.  By  this 
means  most  of  the  organic  matters  are  rendered  insoluble. 

ADULTERATION. — Arsenious  acid  is  liable  to  be  mixed  with  chalk  and 
sulphate  of  lirne.  If  the  suspected  arsenic  is  heated  in  an  iron  spoon, 
it  ought  to  volatilize.  If  it  contains  chalk  and  sulphate  of  lime,  they 
remain  behind. 


ARSENIC.  299 

REFERENCES.  On  the  solubility  of  Arsenious  Acid,  see  a  notice  of  the  pa* 
pers  of  Bucholz  and  Fisher,  in  Ann.  of  Phil.  v.  29.  vii.  33.  Christison  on 
the  taste  of  Arsertic,  Edin.  Med.  and  Surg.  Jour,  xxviii.  95.  On  the  Tests 
of  Arsenic^  see  Christison,  in  Edin.  Medico- Chirurgical  Trans,  ii.  and  in 
Edin.  Med.  and  Surg.  Jour.  xxii.  and  the  Treatise  on  Poisons  by  the  same 
author ;  Forbes,  in  Edin.  Med.  and  Surg.  Jour,  xxxii. ;  R.  Phillips,  in  Ann' 
of  Phil.  xxvi.  298  ;  and  Beck's  Med.  Juris.  383. 

Arsenic  Acid. — Atom.  Num.  57'7 — Symb.  2%  O+As. 

PROPERTIES.  A  white  concrete  substance,  with  a  sour  metallic  taste; 
it  reddens  vegetable  blues,  and  combines  with  bases  forming  salts, 
termed  arseniates ;  attracts  moisture  from  the  air,  and  dissolves  in  five 
or  six  times  its  weight  of  cold,  and  in  a  still  smaller  quantity  of  hot 
water  ;  it  forms  irregular  grains  when  its  solution  is  evaporated,  but 
does  not  crystallize  ;  when  strongly  heated  it  fuses  into  a  glass  which 
is  deliquescent ;  but  when  urged  by  a  very  strong  red  heat  it  is  re- 
solved into  oxygen  and  arsenious  acid  :  it  is  an  active  poison. 

This  acid  may  be  formed  by  dissolving  one  part  of  arsenious  acid  in 
six  parts  of  concentrated  nitric  acid,  and  distilling  the  solution  to  per- 
fect dry  ness.  It  is  found  in  nature  in  combination  with  several  of  the 
metallic  oxides. 

ARSENIC  AND  CHLORINE. 

Chloride  of  Arsenic. — Atom.  Num.  90-87 — Symb.  1 J  Cl+As. 

SYN.     Fuming  liquor  of  Arsenic.     Butter  of  Arsenic. 

PROPERTIES.  A  colourless,  very  soluble  liquid,  which  fumes  very 
strongly  on  exposure  to  the  air,  and  is  resolved  by  water  into  muriatic 
and  arsenious  acids  ;  by  the  aid  of  heat  it  dissolves  sulphur  and  phos- 
phorus, which  however  separate  as  the  liquid  cools. 

PREPARATION.  This  chloride  is  prepared  by  submitting  to  distilla- 
tion a  mixture  of  six  parts  of  corrosive  sublimate  with  one  of  arsenic. 
The  same  compound  is  also  formed  when  arsenic  in  powder  is  thrown 
into  a  jar  full  of  dry  chlorine  gas. 

According  to  Berzelius  there  is  another  chloride  of  arsenic,  con- 
taining a  less  proportion  of  chlorine  than  the  above  ;  [Traite  de  Chim. 
ii.  41 1]  and  that  prepared  by  the  process  of  Dumas  is  perhaps  also  dis- 
tinct from  both. — Brandes  Jour.  N.  S.  i.  234. 

ARSENIC  AND  BROMINE. 

When  arsenic  is  brought  into  contact  with  bromine,  the  two.  bodies 
unite,  according  to  Serullas,  with  the  disengagement  of  light.  Arse- 
nic is  to  be  added  in  small  quantities  to  the  bromine  until  it  ceases  to 
produce  deflagration,  when  the  mass  is  to  be  distilled.  The  bromide 
comes  over  in  the  form  of  a  colourless  and  yellowish  liquid  and  crys 
tallizes  in  the  recipient. — Berzelius ,  ii.  44*2. 


300  ARSENIC. 


ARSENIC  AND  IODINE. 

These  two  bodies  unite  and  form  a  deep  red  compound  which  de- 
composes water,  and  affords  arsenic  and  hydriodic  acids.  It  has  been 
made  the  subject  of  a  memoir  by  M.  Plisson. — Ann.  de  Chim.  et  de 
Phys.  Nov.  1828. 

Fluoride  of  Arsenic  is  a  fuming,  colourless  liquid,  which  by  the  ac- 
tion of  water  completely  decomposes  glass.  It  has  been  examined  by 
Unverdorben. — Berzelius,  ii.  243. 

ARSENIC  AND  HYDROGEN. 

Hydruret  of  Arsenic^   or   Jlrseniuretted  Hydrogen. — Atom. 
Num.  39-2— Symb.  } £  H+As. 

Discovered  by  Scheele  and  obtained  in  a  pure  form  according  to 
Soubeirain,  by  fusing  arsenic  with  its  own  weight  of  granulated  zinc, 
and  decomposing  the  alloy  with  strong  muriatic  acid. 

PROPERTIES.  A  colourless  gas,  having  a  fetid  odour  like  that  of  gar- 
lic ;  its  specific  gravity  according  to  Dumas  is  2-695  ;  it  extinguishes 
bodies  in  combustion,  but  is  itself  kindled  by  them,  and  burns  with  a  blue 
flame  ;  it  instantly  destroys  small  animals  that  are  immersed  in  it,  and 
is  poisonous  in  a  high  degree,  having  proved  fatal  to  a  German  phi- 
losopher, M.  Gehlen ;  water  absorbs  one-fifth  of  its  volume,  and  ac- 
quires the  odour  of  the  gas  ;  it  does  not  possess  acid  properties  ;  it  is 
decomposed  by  various  agents,  as  heat,  atmospheric  air,  chlorine  and 
iodine,  and  with  oxygen  it  forms  an  explosive  mixture. 

Gay  Lussac  has  also  described  a  solid  compound  of  arsenic  and  hy- 
drogen, separating  in  the  form  of  chesnut  brown  coloured  flocks,  dur- 
ing the  action  of  water  upon  an  alloy  of  potassium  and  arsenic.  Its 
composition  is  unknown. — Tkenard,  Traite  de  Chim.  i.  500. 

ARSENIC  AND  SULPHUR. 

% 

Chemists  differ  as  to  the  number  of  definite  compounds  formed  by 
these  bodies.  Some  assert  that  there  are  but  two  ;  others  that  there 
are  three,  while  Berzelius,  in  his  treatise,  describes  no  less  than  five. 
I  shall  adopt  the  view  of  these  compounds  contained  in  Dr.  Turner's 
elements. 

ProtosuJphuret  of  Arsenic. — Jltoin  Num.  53  7 — Symb.  S-f-As. 

SYN.     Sulfide  Hyparscnicux. — Berzelius. 

This  sulphuret  occurs  native,  and  is  known  in  mineralogy  by  the 
name  of  Realgar.  It  may  be  formed  artificially  by  heating  arsenious 
acid  with  about  half  its  weight  of  sulphur,  until  the  mixture  is  brought 
into  a  state  of  perfect  fusion.  The  cooled  mass  is  crystalline,  trans- 
parent, and  of  a  ruby  red  colour  ;  and  may  be  sublimed  in  close  ves- 
sels without  change. 


ARSENIC.  301 

Scsquisulphuret  of  Arsenic. — Atom.  Num.  61-7 — Symb.  1|S 

-fAs. 
SYN.     Sulfide  Arsenieux. — Berzelius. 

Occurs  in  nature,  and  known  by  the  name  of  Orpiment.  Formed 
artificially  by  fusing  together  equal  parts  of  arsenious  acid  and  sulphur; 
or  better,  by  transmitting  a  current  of  sulphuretted  hydrogen  gas 
through  a  solution  of  arsenious  acid. 

PROPERTIES.  This  compound  has  a  rich  yellow  colour  ;  it  fuses 
readily  when  heated,  and  becomes  crystalline  on  cooling,  and  in  close 
vessels  may  be  sublimed  without  "change.  It  is  dissolved  with  great 
facility  by  the  pure  alkalies,  and  yields  colourless  solutions. 

USES.  Orpiment  is  employed  as  a  pigment,  and  is  the  colouring- 
principle  of  the  paint  called  King's  Yellow.  M.  Braconnot  has  pro- 
posed it  likewise  for  dying  silk,  woollen,  or  cotton  stuffs  of  a  yellow 
colour.  For  this  purpose  the  cloth  is  soaked  in  a  solution  of  orpiment 
in  ammonia,  and  then  suspended  in  a  warm  apartment.  The  alkali 
evaporates,  and  leaves  the  orpiment  permanently  attached  to  the  fibres 
of  the  cloth. — Ann.  de  Cliim.  et  de  P/iys.  xii.  or  Branch?  s  Jour.  ix.  184. 

Persulphuret  of  Arsenic. — Atom.  Num.  77 '7 — Symb.  2% 

S+As. 

This  sulphuret  has  a  colour  very  similar  to  orpiment  ;  it  is  dissolved 
by  pure  alkalies,  fuses  by  heat,  and  may  be  sublimed  in  close  vessels 
without  decomposition. 

It  is  prepared  by  transmitting  sulphuretted  hydrogen  gas  through  a 
moderately  strong  solution  of  arsenic  acid  ;  or  by  saturating  a  solution 
of  arseniate  of  potassa  or  soda  with  the  same  gas,  and  acidulating  with 
muriatic  or  acetic  acid.  The  oxygen  of  the  acid  combines  with  the 
hydrogen  of  the  gas,  and  the  persulphuret  of  arsenic  subsides. 

The  experiments  of  Orfila  have  proved  that  the  sulphurets  of  arse- 
nic are  poisonous,  though  in  a  much  less  degree  than  arsenious  acid. 
The  precipitated  sulphuret  is  more  injurious  than  the  native  orpi- 
ment. 

ARSENIC    AND    THE    METALS. 

Arsenic  combines  with  most  of  the  metals,  which  it  generally  ren- 
ders brittle,  even  though  in  very  small  quantity.  Many  of  these  alloys 
are  found  in  nature,  and  are  known  by  the  name  of  jJrseniurcts. 

The  alloy  of  three  parts  of  tin  and  one  part  of  arsenic,  is  white, 
very  brilliant  and  brittle  ;  it  crystallizes  in  large  plates,  is  more  fusible 
than  arsenic,  but  less  so  than  tin.  It  is  employed  in  the  laboratory 
in  the  preparation  of  arseniuretted  hydrogen,  and  is  formed  by  heating 
a,  mixture  of  three  parts  of  tin  and  two  of  arsenic  in  a  covered  cruci- 
ble. The  alloy  of  copper  and  arsenic  is  white,  and  so  very  similar  in 
its  appearance  to  silver,  as  to  be  substituted  for  it. 

ARSENIOUS    ACID    AND    SALIPFABLE    BASES. 

These  compounds,  termed  Arsenites,  have  not  been  much  examined. 
The  Ars&nitcs  of  Potassa,  Soda  and  Ammonia,  are  soluble  and  incapa- 

T 


302  ARSENIC. 

ble  of  crystallizing;  and  they  may  be  easily  prepared  by  boiling  a  so- 
lution of  these  alkalies  in  arsenious  acid.  The  other  arsenites  are  in- 
soluble, or,  at  most,  sparingly  soluble  in  pure  water  ;  but  they  are  dis- 
solved by  an  excess  of  their  own  acid,  with  great  facility  by  nitric  acid, 
and  by  most  other  acids  with  which  their  bases  do  not  form  insoluble 
compounds.  The  insoluble  arsenites  are  easily  formed  by  the  way  of 
.  double  decomposition. 

On  exposing  the  arsenites  to  heat  in  close  vessels,  either  the  arseni- 
ous acid  is  dissipated  in  vapour,  or  they  are  converted,  with  disen- 
gagement of  some  metallic  arsenic,  into  arseniates.  Heated  with  char- 
coal or  black  flux,  the  acid  is  reduced  with  facility. 

The  soluble  arsenites,  if  quite  neutral,  are  characterized  by  forming 
a  yellow  Arsenite  of  Silver  when  mixed  with  the  nitrate  of  that  base, 
and  a  green  Arsenite  of  Copper,  Scheeles  green,  with  sulphate  of  cop- 
per. When  acidulated  with  acetic  or  muriatic  acid,  sulphuretted  hy- 
drogen causes  the  formation  of  orpiment.  The  insoluble  arsenites  are 
all  decomposed  when  boiled  in  a  solution  of  carbonate  of  potassa  or 
soda. 

The  Artenite  of  Potassa  is  the  active  ingredient  in  the  Liquor  Potas- 
SCE  Jlrsenitis  of  the  U.  S.  Pharmacopeia  and  in  Fowler's  mineral  solution 
or  tasteless  ague  drop. 

ARSENIC  ACID  AND  SALIFIABLE  BASES, 

These  compounds,  termed  Arseniates,  resemble  the  phosphates  in 
this  as  in  other  respects,  that  though  carefully  neutralized  when  in  so« 
lution,  yet  when  concentrated  by  evaporation,  they  crystallize  with 
an  excess  of  base. 

Arseniate  of  Ammonia  is  formed  by  saturating  arsenic  acid  with  am- 
monia ;  rhomboidal  prisms  are  obtained  on  evaporation,  which,  when 
gently  heated,  effloresce  and  evolve  ammonia. 

Biarseniate  of  Potassa. — This  salt  occurs  in  four-sided  rectangular 
prisms,  terminated  by  very  short  four-sided  pyramids  ;  is  permanent 
in  the  air  and  has  a  saline  cooling  taste  ;  is  soluble  in  about  five  times 
its  weight  of  cold  water,  but  is  insoluble  in  alcohol. 

It  may  be  formed  by  adding  excess  of  arsenic  acid  to  potassa,  or  by 
distilling  in  a  retort  equal  weights  of  nitre  and  arsenious  acid. 

Arseniate  of  Soda  forms  large  crystals,  having  the  same  shape  as 
phosphate  of  soda,  which  effloresce  by  exposure  to  a  dry  atmosphere  ; 
it  has  a  cooling  taste,  resembling  that  of  carbonate  of  soda,  but  less 
strong  ;  is  soluble  in  about  four  times  its  weight  of  cold  water,  and 
the  liquid  has  alkaline  properties  ;  it  undergoes  watery  fusion  ;  its  so- 
lution when  dropped  into  most  earthy  and  metallic  salts,  occasions 
precipitates,  the  peculiar  appearances  of  which,  are  exhibited  by  Dr. 
Thomson,  in  a  table  published  in  the  Ann.  of  Phil.  xv.  83. 

Arseniates  of  Lime. — According  to  Mr.  Dalton  lime  and  arsenic  acid 
combine  in  several  proportions,  forming  an  insoluble,  a  soluble  and  a 
neutral  arseniate. 

Arseniate  of  Baryta. — An  insoluble  salt,  formed  by  mixing  neutral 
arseniate  of  soda  with  nitrate  of  baryta. 

Arseniates  of  Iron. — There  are  three  native  arseniates  of  iron,  exactly 
similar  in  their  composition  to  the  analogous  phosphates  of  iron. 


MOLYBDENUM.  303 

Arteniate  of  Zinc,  is  precipitated  in  the  form  of  a  white  insoluble 
powder  when  arsenic  acid  or  an  alkaline  arseniate  is  added  to  sulphate 
of  zinc. 

Arseniate  of  Tin — is  a  white  insoluble  powder,  precipitated  by  ad- 
ding arseniate  of  potassa  to  muriate  of  tin. 

drseniate  of  Copper,  is  formed  by  adding  an  alkaline  arseniate  to  ni- 
trate of  copper.  It  is  a  blue  insoluble  powder.  —  See  Chevenix  in  Phil. 
Trans,  for  1801. 

Arseniate  of  Lead. — This  salt  occurs  native  in  the  form  of  crystals, 
in  Saxony  and  in  Cornwall,  Eng.  It  may  be  formed  artificially  by 
pouring  arsenic  acid  into  any  of  the  soluble  salts  of  lead,  when  it  falls 
in  the  form  of  a  white  powder,  insoluble  in  water,  but  soluble  in  dilute 
nitric  acid,  by  which  means  we  can  separate  it,  in  analysis,  from  sul- 
phate of  lead. 

REFERENCES.  Chevenix  in  Phil.  Trans,  for  1801.  Thomson  on  Arse- 
nic and  the  Arseniates,  Ann.  of  Phil.  xv.  81.  Theuard,  Traite  de  Chin.  iii. 
433. 

SECTION  XXII. 

MOLYBDENUM. 

Jitom.  Num..  47-7.— Symb.  Mo.—Sp.  gr.  8-625. 

Discovered  by  Scheele  in  1778,  but  hitherto  has  been  obtained  only  in 
small  quantities,  and  is  known  imperfectly. 

PROPERTIES.  A  brittle  metal  of  a  yellowish  white  colour  and  very 
infusible  ;  it  has  a  specific  gravity  of  8-615,  to  8 '636  according  to  Bu- 
cholz  ;  when  heated  to  a  dull  red  in  open  vessels,  it  is  converted  into 
an  oxide,  and  at  a  still  higher  temperature  it  is  converted  into  an  acid. 

EXTRACTION.  When  the  native  sulphuret  of  molybdenum,  in  fine 
powder,  is  digested  in  nitro-muriatic  acid  until  the  ore  is  completely 
decomposed,  and  the  residue  is  briskly  heated  in  order  to  expel  sulphu- 
ric acid,  molybdic  acid  remains  in  the  form  of  a  white  heavy  powder. 
From  this  acid  metallic  molybdenum  may  be  obtained  by  exposing  it 
with  charcoal  to  the  strongest  heat  of  a  smith's  forge  ;  or  by  conduct- 
ing over  it  a  current  of  hydrogen  gas,  while  strongly  heated  in  a  tube 
of  porcelain. — Berzelius. 

MOLYBDENUM  AND  OXYGEN. 

According  to  Berzelius  there  are  three  compounds  of  molybdenum 
and  oxygen,  viz.  two  oxides  and  an  acid. 

Protoxide  of  Molybdenum.- — Atom.  Num.  55'7 — Symb.  O-f- 

Mo. 

A  dark  coloured  compound,  which  forms  salts  with  acids,  and  when 
heated  in  the  open  air  is  converted  into  the  deutoxide.  It  is  prepared 
by  adding  muriatic  acid  to  the  solution  of  a  molybdate,  and  digesting 
with  distilled  zinc.  For  details,  see  Berzelius,  ii.  470. 


304  MOLYBDENUM. 

Deutoxide  of  Molybdenum. — Jltom.  Num.  63-7 — Synth.  2O 
+  Mo. 

This  oxide  may  be  obtained  in  the  form  of  a  hydrate,  by  digesting 
a  mixture  of  molybdic  acid,  metallic  molybdenum,  and  sulphuric  or 
muriatic  acid,  till  the  colour  of  the  liquid  becomes  a  deep  red.  When 
this  liquid  is  treated  with  ammonia,  a  rust-yellow  hydrated  deutoxide  is 
precipitated,  which  dissolves  in  acids  and  yields  salts  whose  solutions 
are  red,  but  become  black,  when  evaporated  to  dryness. — Berzelius }  ii. 
473. 

Molybdic  Acid.— Atom.  JVum.  tl'7—Symb.  3O+Mo. 

A  white  powder,  of  the  specific  gravity  of  3-4  ;  it  has  a  sharp  me- 
tallic taste;  reddens  litmus  paper  ;  is  very  sparingly  soluble  in  water  ; 
forms  salts  with  salifiable  bases,  but  as  Berzelius  observes,  it  performs 
the  part  of  a  base  towards  the  stronger  acids. 

MOLYBDENUM   AND  FLUORINE. 

Fluomolybdic  Acid.  — This  acid,  which  jjM  first  examined  by  Berze- 
lius in  1824,  may  be  obtained  by  dissolving  molybdic  acid  in  fluoric 
acid.  It  has  an  acid,  metallic  and  disagreeable  taste,  combines  with 
bases  and  forms  Fluomolybdat.es.  It  is  supposed  to  consist  of  one  atom 
fluoric  acid-f-one  atom  molybdic  acid.  —  Thomson,  Jnorg.  Chem.  ii.  202. 

MOLYBDENUM  AND   CHLORINE. 

With  chlorine  molybdenum  combines  in  three  proportions,  forming 
compounds  equivalent  to  its  three  oxides.  The  first  is  red  and  a  little 
volatile.  The  second  is  black,  very  fusible,  very  volatile,  and  crys- 
tallizes in  a  black  mass,  of  a  brilliant  colour  like  iodine,  which  it  re- 
sembles also  in  the  colour  of  its  gas.  The  third  is  colourless  and  crys- 
tallizes in  scales.  —  Berzdius. 


MOLYBDENUM  AND  SULPHUll. 

Bisvlpfiuret  of  Molybdenum. — Atom.  JVum.  79-7 — Symb.  2$ 
-ffifa 

A  sectile  compound  of  a  metallic  lustre,  found  native,  and  prepared 
artificially  by  heating  one  part  of  molybdic  acid  with  five  parts  of  sul- 
phur. 

The  native  mineral  resembles  graphite  or  plumbago,  and  was  for- 
merly confounded  with  it.  It  occurs  exclusively  in  primitive  rocks, 
and  i»  found  in  various  parts  of  the  United  States.  These  two  mine- 
rals may  be  very  well  distinguished  by  the  streak  on  white  china  ;  that 
of  plumbago  is  grayish  black, — that  of  sulphuret  of  molybdenum  has 
an  olive  green  tinge. — Cleaveland's  Mineralogy. 

Berzelius  also  describes  another  sulphuret  of  this  metal,  consisting 
of  one  proportion  of  the  metal  and  three  proportions  of  sulphur.  It 
is  of  a  ruby  colour,  transparent  and  crystallized. — Traite  de  Chim.  ii. 
482. 


CHROMIUM.  305 


MOLYBDIC    ACID    AND    SALIFIABLE    BASES. 

The  Molybdotes  appear  to  be  numerous,  but  they  have  not  been  at- 
tentively examined.  According  to  Dr.  Thomson  the  molybdates  of 
potassa,  soda,  ammonia,  lime,  magnesia,  cobalt  and  rhodium  are  solu- 
ble in  water.  The  other  molybdates  mentioned  in  his  table  are  insolu- 
ble or  nearly  so.  [First  Prin.  ii.  60.]  These  salts  may  be  procured  in 
a  manner  similar  to  the  analagous  compounds  of  chromic  acid.  Mo- 
tybdate  of  Lead  is  found  native,  principally  in  crystals  of  different 
shades  of  yellow. 

REFERENCES.  For  further  information  concerning  tJds  metal  and  its  com- 
pounds^ see  Scheele's  Chem.  Essays ,  the  elaborate  experiments  of  Bucholz, 
in  Gehlen's  Jour.  iv.  618,  or  Repert  of  Arts>  %d  ser.  x.  373,  433;  and  the 
notices  of  its  Alloys  and  Amalgams,  from  CreWs  Annals,  in  Thomson's 
Syst.  of  Chem.  i. 


SECTION  XXIII. 
.CHROMIUM. 

Atom.  Num.  2S.—  Symb.  Cr.—Sp.  gr.  53. 

Chromium  was  discovered  in  the  year  1797,  by  Vauquelin,  in  a  beau- 
tiful red  mineral,  the  native  chromate  of  lead.  It  has  since  been  de- 
tected in  the  mineral  called  Chromate  of  Iron,  which  occurs  abundant- 
ly in  several  parts  of  Europe  and  America. 

PROPERTIES.  This  metal  is  of  a  white  colour,  with  a  shade  of  yel- 
low, and  has  a  distinct  metallic  lustre  ;  it  is  brittle,  very  infusible,  and 
with  difficulty  attacked  by  acids,  even  by  the  nitro-muriatic  ;  its  spe- 
cific gravity  has  been  stated  at  5'9  ;  but  Dr.  Thomson  found  it  a  little 
above  5  ;  when  fused  with  nitre,  it  is  oxidized,  and  converted  into 
chromic  acid. 

PREPARATION.  Chromium,  which  has  hitherto  been  procured  in 
very  small  quantity,  owing  to  its  powerful  attraction  for  oxygen,  may 
be  obtained  by  exposing  the  oxide  of  chromium,  mixed  with  charcoal, 
to  the  most  intense  heat  of  a  smith's  forge. 

REFERENCES.  Vauquelin  on  Chrome,  Ann.  de  Chim.  xxv.  or  Tilloch's 
Phil.  Mag.  i.  279,  361.  An  elaborate  Memoir  on  Chromium  and  iis  com- 
pounds, by  Dr.  Thomson,  in  the  Phil.  Trans,  for  1827,  noticed  in  Phil.  Mag. 
&nd  Ann.  i,  452. 

CHROMIUM    AND  OXYGEN. 

Chromium  and  oxygen  combine  in  two  proportions,  forming  the 
green  oxide,  and  chromic  acid. 


Protoxide  of  Chromium.  —  Atom.  Num.  40  —  Symb.  IJO- 

PROPERTIES.     A   substance  of  a   green  colour,  exceedingly  infusi- 
ble and  suffering  no  change  by  heat  ;  it  is  insoluble  in  water,  and  after 


306  CHROMIUM. 

being  strongly  heated,  resists  the  action  of  the  most  powerful  acids  ; 
deflagrated  with  nitre,  it  is  oxidized  to  its  maximum,  and  is  thus  recon- 
verted into  chromic  acid;  fused  with  borax  or  vitreous  substances, 
it  communicates  to  them  a  beautiful  green  colour,  a  property  which 
affords  an  excellent  test  of  its  presence,  and  renders  it  exceedingly 
useful  in 'the  arts  ;  it  unites  with  acids  and  forms  salts  which  have  a 
green  colour. 

PREPARATION  AND  NATIVE  STATE.  This  compound  is  found  native  in 
France,  in  the  form  of  a  green  incrustation.  It  is  the  colouring  mat- 
ter of  the  emerald,  and  exists  in  a  few  other  minerals.  It  is  easily  ob- 
tained by  calcining  to  redness  chromic  acid  or  the  chromate  of  mer- 
cury ;  the  mercury  is  volatilized  with  a  part  of  the  oxygen,  while  the 
protoxide  remains. 

Broicn  Oxide. — A  brown'  compound  of  chromium  and  oxygen,  was 
first  noticed  by  Vauquelin,  and  has  since  been  supposed,  by  some 
chemists,  to  be  a  deutoxide,  by  others,  to  be  chromous  acid.  It  is  pre- 
pared by  passing  a  current  of  sulphurous  acid  gas  through  a  solution 
of  chromate  or  bichromate  of  potassa,  and  washing  and  drying  the  pre- 
cipitate. According  to  Dr.  Thomson  it  is  nothing  more  than  a  com- 
pound of  one  atom  of  chromic  acid  and  six  atoms  of  green  oxide,  and 
is  incapable  of  forming  peculiar  compounds.  [Phil.  Trans.  1827.] 
This  view  is,  in  the  main,  confirmed  by  the  experiments  of  Maus. — 
Ann.  de  Chim.  tt  dc  Phys.  xxxv.  216.  See  also  Bcrzelius,  ii.  456. 

C/iromic  Acid.— Atom.  Num.  52—Symb.  3O-f-Cr. 

PROPERTIES.  Chromic  acid  has  a  dark  ruby-red  colour,  and  forms 
irregular  crystals  when  its  solution  is  concentrated  ;  it  is  very  soluble 
in  water,  has  a  sour  taste,  and  possesses  all  the  properties  of  an  acid  ; 
is  converted  into  the  green  oxide,  with  evolution  of  oxygen,  by  expo- 
sure to  a  strong  heat ;  it  yields  a  muriate  of  the  protoxide,  when  boil- 
ed with  muriatic  acid  and  alcohol,  and  the  direct  solar  rays  have  a 
similar  effect  when  muriatic  acid  is  present.  With  sulphurous  acid, 
it  forms  a  sulphate  of  the  protoxide ;  it  is  characterized  by  its  colour, 
and  by  forming  coloured  salts  with  bases,  the  most  important  of  which 
is  chromate  of  lead. 

PREPARATION.  This  acid  may  be  prepared  by  digesting  chromate  of 
baryta  in  a  quantity  of  dilute  sulphuric  acid  exactly  sufficient  for  com- 
bining with  the  baryta.  The  sulphate  of  baryta  subsides,  and  a  solu- 
tion of  chromic  acid  is  obtained.  Dr.  Thomson  proposes  another  me- 
thod of  preparing  this  acid  by  acting  on  the  green  oxide  with  nitric 
acid  ;  and  Maus  obtains  it  by  decomposing  a  hot  and  concentrated  so- 
lution of  bichromate  of  potassa  with  fluosilisic  acid ;  filtering  the  li- 
quid and  evaporating  to  dryness  in  a  platinum  capsule.  The  acid  thus 
dried  is  then  dissolved  in  the  smallest  possible  quantity  of  water,  to 
exclude  a  portion  of  fluosilicate  of  potassa,  which  has  passed  the  filter, 
and  the  fluid  decanted  ;  for  in  this  state  of  concentration,  chromic 
acid  cannot  be  filtered,  as  it  attacks  paper  and  is  converted  into  oxide 
of  chromium. — Erandes  Jour.  N.  S.  iii.  488. 


CHROMIUM.  307 

CHROMIUM    AND    CHLORINE. 

Chloro chromic  Jlcid  Gas,  or  Chloride  of  Chromium. 

Discovered  by  M.  Unverdorben,  in  1825. 

PROPERTIES.  A  red  coloured  gas,  which  may  be  collected  in  glass 
vessels  over  mercury  ;  it  is  instantly  decomposed  by  water,  and  yields 
a  solution  of  muriatic  and  chromic  acids  ;  it  may  be  regarded  either 
as  a  compound  of  muriatic  and  chromic  acids,  or  of  chlorine  and 
chromium. 

This  compound  is  formed  by  the  action  of  fuming  sulphuric  acid  on 
a  mixture  of  chromate  of  lead  and  chloride  of  sodium. — Edin.  Jour,  of 
Science,  iv.  129. 

Dr.  Thomson  has  also  described  a  red  coloured  liquid  under  the 
name  of  Chloro chromic  Acid,  which  he  obtained  by  the  action  of  con- 
centrated sulphuric  acid  on  the  mixture  of  dry  bichromate  of  potassa 
and  sea-salt.  He  supposes  it  to  consist  of  one  atom  of  chromic  acid 
and  one  of  chlorine,  but  there  are  still  some  doubts  with  regard  to  its 
composition.  —  Thomson,  in  Phil.  Trans,  for  1827,  and  itiorg.  Chem. 

CHROMIUM    AND    FLUORINE. 

Fluochrotnic  Acid  Gas,  or  Fluoride  oj  Chromium. 

PROPERTIES.  A  gaseous  snbstance,  acting  rapidly  upon  glass  with 
the  deposition  of  chromic  acid,  and  the  formation  of  fluosilisic  acid 
gas ;  it  is  absorbed  by  water,  and  the  solution  is  found  to  contain  a 
mixture  of  hydrolluoric  and  chromic  acids  ;  it  is  decomposed  by  the 
watery  vapour  of  the  atmosphere,  so  that  when  mixed  with  air,  red 
fumes  appear,  owing  to  the  separation  of  minute  crystals  of  chromic 
acid. 

This  gas  was  first  obtained  by  M.  Unverdorben,  by  distilling  a  mix 
ture  of  rtuor  spar  and  chromate  of  lead  with  fuming  or  even  common 
sulphuric  acid,  in  a  leaden  retort.  It  may  be  collected  and  kept  for  a 
short  time  in  glass  vessels  coated  with  resin. — Berzelius. 

Sulphuret  of  Chromium. — A  dark  gray  compound,  without  the  me- 
tallic lustre  ;  formed  by  passing  the  vapour  of  sulphuret  of  carbon 
over  the  oxide  of  chromium  heated  to  redness  in  a  porcelain  tube. — 
Berzelius,  ii.  463. 

Phosphuret  of  Chromium. — A  grayish  mass,  obtained  by  subjecting 
phosphate  of  chromium  to  heat  in  a  forge. — Berzelius,  ii.  465. 

CHROMIC  ACID  AND  SALIFIABLE   BASES. 

The  compounds  termed  Chromates,  are  mostly  of  a  red  or  yellow 
colour,  and  on  being  boiled  in  muriatic  acid  mixed  with  alcohol,  the 
chromic  acid  is  at  first  set  free  and  is  then  decomposed,  a  green  muri- 
ate of  the  oxide  of  chromium  being  generated. 


308  CHROMIUM. 

Chromate  of  Potassa.  — ^tom.  Num.  99-15 — Symb. 
(30+Cr.)+(0+Po.) 

PROPERTIES.  An  anhydrous  salt,  having  a  cool  bitter,  and  disa- 
greeable taste ;  it  forms  crystals,  the  primary  shape  of  which  is  a 
right  rhombic  prism,  [Ann.  of  Phil.  xxii.  120,]  and  is  of  an  intense 
lemon  yellow  colour,  with  a  slight  shade  of  orange  ;  is  soluble  to  a 
great  extent  in  boiling  water,  and  in  twice  its  weight  of  the  liquid  at 
60°  F. ;  is  insoluble  in  alcohol  ;  has  an  alkaline  reaction,  from  which 
it  has  been  incorrectly  supposed  to  be  a  sub-salt  ;  its  solution  in  wa- 
ter decomposes  most  of  the  metallic  salts,  furnishing  some  valuable 
pigments. 

PREPARATION.  This  salt,  from  which  all  the  compounds  of  chro- 
mium are  directly  or  indirectly  prepared,  is  made  by  heating  to  redness 
the  native  oxide  of  chromium  and  iron,  commonly  called  Chromate  of 
Iron,  with  an  equal  weight  of  nitrate  of  potassa,  when  chromic  acid  is 
generated,  and  unites  with  the  alkali  of  the  nitre.  After  digesting 
the  ignited  mass  in  water  until  the  chroraate  is  dissolved,  the  solution 
is  neutralized  by  nitric  acid,  and  concentrated  by  evaporation,  in  order 
that  the  nitrate  of  potassa  should  crystallize.  The  residual  liquid  is 
then  set  aside  to  evaporate  spontaneously,  and  the  chroniate  is  gradu- 
ally deposited  in  small  prismatic  crystals. 

Bichromate  of  Potassa. — Atom.  Num.  151*15 — Symb.  2 
(30+Cr.)+(0+Po.) 

This  salt  occurs  in  four-sided  tabular  crystals,  the  primary  form  of 
which  is  an  oblique  rhombic  prism  ;  it  is  of  an  exceedingly  rich  red 
colour,  is  insoluble  in  about  ten  times  its  weight  of  water  at  60°  F.  and 
the  solution  reddens  litmus  paper. 

Bichromate  of  f>otassa  is  made  by  acidulating  the  chromate  with 
sulphuric  acid,  and  allowing  the  solution  to  crystallize  by  spontaneous 
evaporation.  It  is  used  in  dying. 

Chromate  of  Iron  is  found  native  in  Siberia,  France  and  the  United 
States,  in  small  crystalline  grains,  of  an  octahedral  form  ;  but  it  more 
commonly  occurs  massive,  of  a  black  colour,  with  a  slight  metallic 
lustre,  and  hard  enough  to  scratch  glass. 

Chromate  of  Lead— Atom.  Num.  163-5—  Symb.  (3O-f  Cr.) 
+(0+Pb.) 

This  is  a  very  rare  mineral  found  only  in  Siberia.  It  is  prepared 
artificially  by  adding  chromate  of  potassa  to  a  soluble  salt  of  lead.  It  is 
of  a  fine  yellow,  and  is  known  in  commerce  by  the  name  of  Chrome 
Yellow. 

Dichromate  of  Lead. — Atom.  Num.  275.— Symb.  (30+Cr.) 
+  (20+Pb.) 

A  salt,  called  also  the  Subchromate  of  Lead,  of  a  beautiful  red  co- 
lour, formed  by  boiling  carbonate  of  lead  with  excess  of  chromate  of 


VANADIUM.  309 

potassa.     It  is  recommended  by  Mr.  Badams  as  a  pigment. — Ann.  of 
Phil.  xxv.  303. 

Besides  the  above  there  are  chromates  of  ammonia,  soda,  lime  and 
magnesia,  which  are  soluble  and  crystallizable  ;  chromates  of  baryta 
and  strontia,  which  are  difficultly  soluble  ;  and  those  of  silver,  mer- 
cury, copper  and  uranium,  the  colours  of  which  are  crimson,  red, 
apple-green  and  yellow.  The  insoluble  chromates  are  formed  by 
mixing  soluble  salts  of  those  bases,  with  chromate  of  potassa  or 
soda. 

REFERENCES.  For  further  details  concerning  the  corn-pounds  of  Chromic 
Acid  with  bases,  see  Vauquelint  Ann.  de  Cldm.  Ixx.  Dr.  Jo/in,  on  some 
unkninvn  combinations  of  Chromic  Acid,  Ann.  of  Phil.  iv.  424  ;  Dr.  Thorn, 
son,  in  the  same  work,  xvi.  321  ;  Grouvelle,  Ann.  de  Clrim.  et  de.  Phys.  xvii.S 
and  Stokes,  on  some  new  double  Chromates,  hil.  Mag.  and  Ann.  ii.  427. 
On  the  Poisonous  properties  of  the  Chromates,  see  Christisoif.cn  Poisons* 
37'2',  and  Dr.  Duncan,  in  the  Edin.  Med.  and  tiurg.  Jour.  xxvi.  133. 

SECTION  XXIV. 

VANADIUM 

Atom.  Num.  68-5.—  Symb.  V. 

Vanadium,  so  called  from  Vtinadis,  the  name  of  a  Scandanavian  di- 
vinity, was  discovered  by  Sefstrom  in  1830,  in  the  iron  from  the  forges 
of  Eckersholm  in  Sweden  ;  and  in  1831  it  was  found  in  an  ore  of  lead 
from  Wanlock  Head,  by  Mr.  Jo.hnston  of  Edinburgh.*  It  has  been 
obtained  by  heating  vanadic  acid  in  contact  with  potassium  and  by  the 
decomposition  of  the  chloride  of  vanadium. 

PROPERTIES.  This  metal  as  obtained  by  means  of  potassium,  is  a 
heavy  black  powder,  with  very  little  lustre.  But  when  prepared  by 
the  decomposition  of  the  chloride,  it  has  a  white  colour  resembling  sil- 
ver, a  strong  metallic  lustre,  but  it  is  extremely  brittle.  It  is  not  oxid- 
ized by  either  air  or  water,  is  not  acted  on  by  boiling  sulphuric,  muriat- 
ic, or  hydrofluoric  acid,  but  is  attacked  by  the  nitric  and  nitro-muriat- 
ic  acids,  and  the  solution  has  a  fine  dark  blue  colour. 


*  According  to  Hurnboldt  it  appears  that  this  metal  had  been  discovered 
in  Mexico,  by  M.  del  Rio,  in  a  brown  lead  ore,  found  in  the  district  of  Zimam- 
pa?.  M.  del  Rio  gave  it  the  name  of  Erythronium,  but  was  afterwards  in- 
duced to  suppose  it  merely  an  impure  chrome.  Since  the  discovery  of  Sefs- 
trom,  however,  the  brown  lead  ore  of  Ziinampas  has  again  been  analyzed? 
and  a  simple  substance,  precisely  similar  to  that  found  in  the  iron  by  Sefstrom' 
obtained  from  ii.-~Jour.  of  Royal  Institution,  ii.  562. 


VANADIUM. 

VANADIUM    AND    OXYGEN. 

Vanadium  combines  with  oxygen  in  three  proportions. 

Protoxide  of  Vanadium. —A torn.  Num.  76*5 — Symb.  O+V. 

A  dark  brown  or  black  compound,  soluble  in  nitric  acid  and  in  aqua 
regia,  but  does  not  form  salts.  It  is  obtained  by  reducing  vanadic  acid 
by  hydrogen  gas. 

Deut-  or  Binoxide  of  Vanadium. — Atom.  Num.  84'5 — Symb. 
20+V. 

A  black  and  pulverulent  substance,  very  infusible  and  insoluble  in 
water  ;  heated  in  the  air  it  attracts  oxygen  and  is  converted  into  vana- 
dic acid ;  forms  salts  with  the  acids,  which  when  anhydrous  are  dark- 
brown,  and  when  they  contain  water,  of  a  deep  blue  like  the  salts  of 
copper ;  it  also  combines  with  alkalies,  forming  brown  soluble  com- 
pounds. 

Vanadic  Acid.— Atom.  Num.  92-5—  Symb.  3O+V. 

PROPERTIES.  This  compound  is  a  yellow  powder,  tasteless,  sparing 
ly  soluble  in  alcohol  and  water,  to  which  liquid  it  imparts  a  yellow  co- 
lour ;  fuses  at  a  red  heat  and  on  cooling  crystallizes  in  beautiful  pris- 
matic crystals,  transparent  at  the  edges,  of  a  reddish  brown  colour  and 
a  high  degree  of  lustre  ;  it  forms  with  bases  neutral  salts  which  in 
general  are  colourless,  and  acid  salts  of  a  bright  orange  colour  ;  gives 
also  saline  combinations  with  the  acids  ;  may  be  distinguished  from  all 
other  acids  except  the  chromic  by  its  colour  and  from  this  by  the  ac- 
tion of  deoxidizing  substances,  which  give  a  blue  solution  with  the  for- 
mer and  a  green  with  the  latter. 

Vanadic  Add  forms  colourless  as  well  as  coloured  Salts. — One  of  the 
most  singular  facts  with  regard  to  this  acid  is  that  its  neutral  salts  are 
yellow  at  one  time  and  colourless  at  another  without  suffering  any  ap- 
preciable change  in  composition.  Thus  on  neutralizing  vanadic  acid 
with  ammonia  a  yellow  salt  is  obtained,  the  solution  of  which  gradual- 
ly becomes  colourless  if  kept  for  some  hours,  and  suffers  the  same 
change  rapidly  when  heated.  The  solution,  as  it  is  coloured  or  colour- 
less, gives  a  white  residue  by  evaporation,  and  a  yellow  or  white  pre- 
cipitate with  a  salt  of  lead  or  baryta.* 

PREPARATION.  By  heating  the  vanadiate  of  ammonia  in  an  open 
vessel  and  well  stirred,  the  whole  mass  acquires  a  dark  red  colour,  and 

*  A  ne\v  and  almost  indelible  ink,  is  prepared  by  ISerzelius  from  vanadium. 
It  is  formed  by  mixing  the  vanadiate  of  ammonia  with  mfu-ion  of  galls  ;  a  black 
liquid  is  produced  which  is  the  best  writing  ink  that  can  be  formed.  Acids 
render  it  blue  but  do  not  obliterate  it;  the  alkalies  when  sufficiently  diluted 
not  to  act  upon  the  paper  do  not  dissolve  it,  arid  chlorine  which  destroys  the 
black  colour  does  not,  however,  efface  the  writing  even  when  water  is  after- 
wards suffered  to  run  over  it. — Phil.  Mag.  and  Ann.  N.  S.  xi.  16. 


VANADIUM.  311 

« 

pure  vanadic  acid  is  obtained  ;  but  a  red  heat  should  be  avoided, 
since  fusion  would  thereby  be  occasioned,  and  free  exposure  of  every 
part  to  the  atmosphere  prevented. 

VANADIUM    AND    CHLORINE. 

Bichloride  of  Vanadium— is  prepared  by  digesting  a  mixture  of  the 
vanadic  and  muriatic  acids,  deoxidizing  any  undecomposed  vanadic 
acid  by  sulphuretted  hydrogen  and  evaporating  the  solution  to  dryness. 
A  brown  residue  is  obtained,  which  yields  a  blue  solution  with  water, 
part  being  left  as  an  insoluble  sub-salt.  It  may  also  be  generated  by 
acting  directly  on  the  ignited  deutoxide  with  strong  muriatic  acid.  As 
thus  obtained  its  solution  is  brown  instead  of  blue,  though  in  composi- 
tion it  seems  identical  with  the  preceding. — Turner. 

The  ter-C/doride  may  be  formed  by  transmitting  a  current  of  dry 
chlorine  gas  over  a  mixture  of  protoxide  of  vanadium  and  charcoal 
heated  to  low  redness,  when  the  terchloride  passes  over  in  vapour,  and 
condenses  in  the  form  of  a  yellow  liquid,  from  which  free  chlorine  may 
be  removed  by  a  current  of  dry  air.  It  is  converted  by  water  into  mu- 
riatic and  vanadic  acid,  and  atmospheric  moisture  produces  the  same 
change  indicated  by  the  escape  of  red  fumes.  —  Turner. 

Compounds  of  vanadium  and  bromine,  iodine,  fluorine  and  cyanogen, 
may  be  formed  by  dissolving  deutoxide  of  vanadium  in  hydrobromic, 
hydriodic,  hydrofluoric  and  prussic  acids. 

VANADIUM    AND    SULPHUR. 

Bisulphuret  of  Vanadium — is  a  compound  of  a  brown  colour  which 
becomes  black  when  it  is  dried  and  which  takes  fire  when  heated.  It 
is  obtained  by  heating  the  deutoxide  of  vanadium  to  redness  in  a 
current  of  sulphuretted  hydrogen,  or, by  mixing  with  a  salt  of  the  deu- 
toxide of  vanadium  a  hydrosulphuretted  alkali  until  the  precipitate  at 
first  formed  is  re-dissolved,  and  then  decomposing  the  deep  purple-col- 
oured solution  by  sulphuric  or  muriatic  acid. 

Ter-sulphuret  of  Vanadium — is  formed  by  acidulating  a  solution  of 
vanadic  acid  in  a  hydrosulphuretted  alkali  by  muriatic  or  sulphuric 
acid.  It  has  a  much  lighter  brown  colour  than  the  bisulphuret,  becomes 
almost  black  in  drying,  and  is  resolved  by  a  red  heat  in  close  vessels 
into  the  bisulphuret  with  loss  of  water  and  sulphur.  It  is  soluble  in 
alkalies  and  alkaline  hydrosulphates,  and  is  oxidized  by  nitric  acid. 


VANADIUM    AND    PHOSPHORUS. 

Phosphuret  of  Vanadium,  is  of  a  leaden-gray  colour,  and  may  be 
formed  by  exposing  to  a  white  heat  phosphate  of  deutoxide  of  vanadi- 
um mixed  with  a  small  quantity  of  sugar. 

REFERENCES.  Berzelms  on  Vanadium,  Phil.  Mag.  and  Ann.  x.  321.  xi. 
7.  Johnston  in  Brewster's  Jour.  N.  S.  v.  318.  Reports  of  the  British  Asso- 
ciation for  1832.  Turner's  Chemistry,  4th  ed. 


312  TUIN7GSTEN. 

SECTION  XXV. 
TUNGSTEN. 

Atom.  Num.  99'7. — Syrnb.  Tu. — Sp.  gr.  l?-4. 

PROPERTIES.'  Colour  grayish  white,  like  that  of  iron,  with  consid- 
erable lustre  ;  it  is  brittle,  nearly  as  hard  as  steel,  and  less  fusible  than 
manganese  ;  it  is  surpassed  in  density  only  by  gold  and  platinum  ;  it 
is  oxidized  by  the  action  of  heat  and  air. 

This  metal  is  obtained  by  exposing  tungstic  acid  to  the  action  of 
charcoal,  or  dry  hydrogen  gas,  at  a  red  heat. 

TUNGSTEN    AND    OXYGEX. 

Chemists  are  acquainted  with  two  compounds  of  this  metal  and  oxy- 
gen, viz  :  an  oxide  and  an  acid. 

Oxide  of  Tungsten. — Atom.  Num.  11 5? — Symb.  2O+Tu. 

PROPERTIES.  A  compound  of  a  brown  or  nearly  black  colour,  depend 
ing  upon  the  mode  of  its  preparation,  which  does  not  so  far  as  is 
known,  unite  with  acids,  and  which,  when  -heated  to  near  redness, 
takes  fire  and  yields  tungstic  acid  ;  it  combines,  according  to  Wbhler, 
with  soda. — Berzelius,  ii.  486. 

PREPARATION.  This  oxide  may  be  formed  by  the  action  of  hydro- 
gen gas  on  tungstic  acid,  at  a  low  red  heat.  But  the  most  convenient 
process  is  that  described  by  Wb'hler.  A  mixture  of  powdered  wol- 
fram and  carbonate  of  potassa  is  fused  ;  the  resulting  tungstate  of 
potassa  is  dissolved  in  water,  arid  a  sufficient  quantity  of  muriate  of 
ammonia  then  added.  The  liquor  is  evaporated  to  dryness,  and  the 
mass  is  fused  in  a  Hessian  crucible,  till  the  muriate  of  ammonia  is  en- 
tirely decomposed  and  evaporated.  By  dissolving  the  fluid  mass  in 
water,  a  black  powder  separates,  which  is  oxide  of  tungsten.  This  is 
boiled  with  a  weak  solution  of  potassa,  to  remove  a  small  quantity  of 
acid  and  difficultly  soluble  tungstate  of  potassa,  and  then  washed  with 
abundance  of  distilled  water. — Ann.  de  (.him.  ttdcPhys.  xxix.  Brundu s 
Jour.  xx.  ]77. 

Tungstic  Add.— Atom.  Num.  123  7— Symb.  3O+Tu. 

PROPERTIES.  Tungstic  acid  is  of  a  yellow  colour,  is  insoluble  in 
water,  and  has  no  action  on  litmus  paper ;  it  forms  salts  with  alka- 
line bases,  called  Tungstates,  which  are  decomposed  by  the  stronger 
acids,  the  tungstic  acid  in  general  falling,  combined  with  the  acid  by 
which  it  is  precipitated  ;  it  has  a  specific  gravity  of  6' 12  ;  is  difficult- 
ly iusible  ;  calcined  in  contact  with  air,  its  yellow  colour  becomes 
deeper  and  passes  to  a  green,  and  after  some  hours  to  a  gray. 

NATIVE  STATE  AND  PREPARATION.  This  acid  has  only  been  found 
in  nature,  combined  with  bases,  in  two  rare  minerals,  the  tungstate  of 
lime,  and  the  tungstate  of  iron  and  manganese,  or  Wolfram.  It  is  ar- 


ANTIMONY.  313 


OV 


mine  acici  ;  oy  wmcn  means  me  laitiatc  ui  uiuo  is  luiiueu,  aim  me 
tungstic  acid  separates  in  the  form  of  a  yellow  powder.  This  is  freed 
from  impurities  by  washing  it  alternately  with  ammonia  and  nitric 
acid.  See  Berzelius,  ii.  487. 

TUNGSTEN  AND  CHLORINE. 

According  to  Wohler,  these  substances  combine  in  three  proper* 
tions. 

Deuto chloride  of  Tungsten. — A  compound,  of  a  deep  red  colour, 
which  sublimes  in  delicate  needles.  It  is  very  fusible,  enters  into  ebu- 
lition  at  a  slightly  elevated  temperature,  and  is  converted  into  a  red 
gas,  of  a  more  intense  colour  than  nitrous  acid  gas.  It  is  obtained  by 
heating  metallic  tungsten  in  a  current  of  chlorine  gas. 

Percfdoride  of  Tungsten. — This  chloride  is  generated  by  heating  the 
oxide  of  tungsten  in  chlorine  gas.  The  action  is  attended  with  the 
appearance  of  combustion,  dense  fumes  arise,  and  a  thick  sublimate 
is  obtained  in  the  form  of  white  scales,  like  native  boracic  acid.  It 
is  volatile  at  a  low  temperature  without  previous  fusion.  It  is  con- 
verted by  the  action  of  water  into  tungstic  and  muriatic  acids,  and 
must,  therefore,  in  composition,  be  proportional  to  tungstic  acid. 

Wohler  has  described  another  chloride  which  is  formed  at  the  same 
time  as  the  last ;  and  though  it  is  converted  into  muriatic  and  tungstic 
acids  by  the  action  of  water,  and  would  thus  seem  identical  with  the 
perchloride  in  the  proportion  of  its  elements,  its  other  properties  are 
nevertheless  different.  It  is  the  most  beautiful  of  all  these  compounds, 
existing  in  long  transparent  crystals,  of  a  fine  red  colour.  It  is  very 
fusible  and  volatile,  and  its  vapour  is  red,  like  that  of  nitrous  acid.  The 
difference  between  this  compound  and  the  chloride  fir^t  described,  has 
not  yet  been  discovered. 

In  addition  to  the  above  compounds,  Berzelius  describes  a  Fluoride 
of  Tungsten,  or  Fluo-tungstic  acid,  and  two  Sulphurets  of  Tungsten. — 
Traite  de  Chim.  ii.  489,  492. 

REFERENCES.  Herzelius  on  Tungsten  and  some  of  its  compounds,  Ann  of 
Phil.  iii.  244.  Bucholz's  experiments  on  Tungsten  and  its  combinations  with 
Oxygen,  Ammonia  and  other  substances,  Ann.  of  P /til.  vi.  198.  Thomson's 
First  Prin.  ii.  6*2.  :  >v 


SECTION  XXVI. 

ANTIMONY. 

Atom.  JVi£0i.  64-6.— %i»6.  Sb*— Sp.  gr.  6*7. 

The  date  of  the  discovery  of  this  metal  is  unknown ;  but  the  man- 
ner of  obtaining  it  was  first  described  by  Basil  Valentine,  in  the  fif- 
teenth century,  in  a  work  entitled  Currus  Triumphal  Antimonii. — It 
was  called  Regulus  of  Antimony. 


*  From  the  latin  word  Stibium. 


314  ANTIMONY. 

PROPERTIES.  A  brittle  metal,  of  a  silvery  white  colour,  scaly  tex- 
ture, and  possessing  considerable  lustre  ;  it  fuses  at  810°  F.  and  when 
slowly  cooled,  sometimes  crystallizes  in  octahedral  or  dodecahedral 
crystals  ;  in  close  vessels  it  may  be  volatilized  and  collected  unchang- 
ed, but  not,  Thenard  asserts,  if  atmospheric  air  be  carefully  excluded, 
and  no  gaseous  matter  be  generated  during  the  process  ;  it  tarnishes  by 
exposure  to  the  atmosphere,  and  when  placed  on  ignited  charcoal,  un- 
der a  current  of  oxygen  gas,  it  burns  with  great  brilliancy,  giving  off 
an  oxide  in  the  form  of  a  dense  yellow  smoke. 

PREPARATION.  Antimony  sometimes  occurs  native  ;  but  its  only 
ore  which  is  abundant,  and  from  which  the  antimony  of  commerce  is 
derived,  is  the  sulphuret.  This  sulphuret  was  long  regarded  as  the 
metal  itself,  and  was  called  Antimony,  or  Crude  Antimony. 

Metallic  antimony  may  be  obtained  either  by  heating  the  native 
sulphuret  in  a  covered  crucible  with  half  its  weight  of  iron  filings  ;  or 
by  mixing  it  with  two-thirds  of  its  weight  of  cream  of  tartar  and  one- 
third  of  nitre,  and  throwing  the  mixture,  in  small  successive  portions, 
into  a  red  hot  crucible.  By  the  first  process,  the  sulphur  unites  with 
iron,  and  in  the  second  it  is  expelled  in  the  form  of  sulphurous  acid  ; 
while  the  fused  antimony,  which  in  both  cases  collects  at  the  bottom 
of  the  crucible,  may  be  drawn  off  and  received  in  moulds.  The  anti- 
mony thus  obtained  is  not  absolutely  pure  ;  and  therefore,  for  chemic- 
al purposes,  should  be  procured  by  heating  the  oxide  with  an  equal 
weight  of  cream  of  tartar. 

ANTIMONY  AND  OXYGEN. 

The  existence  of  three  compounds  of  antimony  and  oxygen  is  now 
generally  admitted  ;  one  of  these  is  a  salifiable  basis,  the  other  two 
are  acids. 

Protoxide  of  Antimony. — Atom.  Num.  76-6 — Symb.  } £ 

O+Sb. 

PROPERTIES.  A  powder  of  a  dirty  white  colour,  which  fuses  at  a  red 
heat  and  forms  on  cooling  an  opaque  crystalline  mass  ;  it  is  very  vola- 
tile, and  may  be  sublimed  in  close  vessels  by  a  strong  heat  ;  when 
heated  in  open  vessels  it  absorbs  oxygen  and  is  converted  into  the 
deutoxide  ;  it  is  the  basis  of  all  the  salts  of  antimony,  and  forms  the 
Tartar  Emetic  when  boiled  with  tartrate  of  potassa. 

PREPARATION.  Oxide  of  antimony  may  be  obtained  by  pouring  mu- 
riate of  antimony  into  water,  washing  the  precipitate  (formerly  called 
Poicder  of  Mgarotk)  first  with  a  weak  solution  of  potassa,  and  after- 
wards with  water,  and  then  drying  it ;  or  by  adding  to  a  solution  of 
Tartar  Emetic  a  solution  of  ammonia,  and  washing  the  precipitate 
with  plenty  of  hot  water.  It  is  also  formed  during  the  combustion  of 
metallic  antimony,  though  not  perhaps  perfectly  pure. 


ANTIMONY.  315 

Antimonious  Acid,  or  Deutoxide  of  Antimony. — Atom.  Num. 
SO'6—Symb.  2O+Sb. 

PROPERTIES.  White  ;  infusible  ;  fixed  in  the  fire  ;  insoluble  in  wa- 
ter, arid  likewise  in  acids,  after  being  heated  to  redness  ;  combines 
with  bases  and  forms  salts  called  rfntimonites. 

This  compound  is  prepared  by  dissolving  metallic  antimony  in  nitric 
acid  and  evaporating  and  igniting  the  product  ;  or  by  dissolving  the 
metal  in  nitro-inuriatic  acid,  decomposing  by  water,  washing  the  pre- 
cipitate and  calcining  it  in  a  platinum  crucible. 

Antimonic  Add,  or  Peroxide  of  Antimony. — Atom.  Num.81'6 
—Symb.  2£O+Sb. 

This  compound  may  be  obtained  by  dissolving  the  metal  in  nitro- 
muriatic  acid,  from  which  it  may  be  precipitated  by  throwing  the  solu- 
tion into  water,  as  it  is  insoluble  in  that  fluid.  When  recently  pre- 
pared it  reddens  litmus  paper,  and  may  be  dissolved  in  water  by  means 
of  muriatic  or  tartaric  acid.  As  thus  obtained  it  is  a  Hydrate,  but  if 
exposed  to  the  temperature  of  600°  F.,  the  water  is  driven  off  and  the 
pure  peroxide  remains. 

PROPERTIES.  This  compound,  when  pure,  is  of  a  lemon  yellow 
colour  ;  is  decomposed  by  exposure  to  a  red  heat ;  is  not  soluble  in 
acids,  but  combines  with  bases,  and  forms  salts,  termed  Antimoni- 
ates. 

REFERENCES.  Ori  the  compounds  of  Antimony  and  Oxygen,  see  Berzeli- 
ws,  ii.  496,  and  Thenard,  ii.  368,  both  of  whom  noiv  recognize  only  three; 
Prout)  in  Aim.  Jour,  de  Phys.  iv.  who  reduces  them  to  two. 

ANTIMONY    AND    CHLORINE. 

Two  distinct  compounds  of  these  bodies  are  now  recognized. 

Sesquichloride  of  Antimony. — Atom.  Num.  117-7 — Symb.  1 J 

Cl+Sb. 

PROPERTIES.  At  common  temperatures  this  compound  is  a  soft 
solid,  and  hence  called  Butter  of  Antimony  ;  it  is  liquified  by  a  gentle 
heat,  and  crystallizes  on  cooling  ;  it  deliquesces  on  exposure  to  the 
air,  and  when  mixed  with  water  is  converted  into  muriatic  acid,  and 
protoxide  of  antimony — or  Muriate  of  Antimony 

It  may  be  obtained  by  throwing  powdered  antimony  into  chlorine, 
or  by  distilling  a  mixture  of  antimony  with  twice  and  a  half  its  weight 
of  corrosive  sublimate. 


316  ANTIMONY. 

Per  chloride  of  Antimony. — Atom.  JYitm.  153-22 — Symb.  2J 
Cl+Sb. 

A  transparent  volatile  liquid,  which  emits  fumes  on  exposure  to  the 
air  and  when  mixed  with  water  is  converted  into  muriatic  acid  and  hy- 
drated  peroxide  of  antimony.  It  is  obtained  by  passing  dry  chlorine 
gas  over  heated  metallic  antimony. — Rose,  in  Jinn,  of  P /til.  xxvi.  416. 

ANTIMONY    AND    SULPHUR. 

The  compounds  of  antimony  and  sulphur  have  been  examined  by 
M.  H.  Rose  ;  according  to  whom  there  are  three. — Jinn,  of  P  hit.  xxvi. 
419. 

BesquisiJjjJiurct  of  Antimony. — Atom.  Num.  8S-6 — Symb.  1J 
S+Sb. 

This  sulphuret,  known  by  the  name  of  Grade  Antimony,  is  found  na- 
tive of  a  lead  gray  colour,  and  which,  though  generally  compact, 
sometimes  occurs  in  acicular  crystals  or  in  rhombic  prisms  ;  it  may  be 
melted  in  close  vessels  without  undergoing  any  change,  hut  when  slow- 
ly roasted  in  a  shallow  vessel,  it  gradually  loses  sulphur  and  attracts 
oxygen,  and  may  then  be  melted  into  a  glassy  substance,  transparent 
at  the  edges,  and  called  Glass  of  Antimony. 

This  sulphuret  may  be  formed  artificially  by  fusing  together  antimo- 
ny and  sulphur,  or  by  transmitting  a  current  of  sulphuretted  hydrogen 
gas  through  a  solution  of  tartar  emetic—  washing  and  drying  the  pre- 
cipitate. This  precipitate,  according  to  Gay  Lussac  and  Dr.  Turner, 
in  a  hydrated  sesquisulphuret  of  antimony. 

When  sulphuret  of  antimony  is  boiled  in  a  solution  of  potassa,  a  li- 
quid is  obtained,  from  which,  as  it  cools,  an  orange-coloured  matter, 
called  Kermes  Mineral,  is  deposited  ;  and  on  subsequently  neutralizing 
the  cold  solution  with  an  acid,  an  additional  quantity  of  a  similar  sub- 
stance, the  Golden  Sulphuret  of  the  Pharmacopeia,  subsides.  Accord- 
ing to  Berzelius  and  Rose,  kermes  is  a  hydrated  sesquisulphuret,  differ- 
ing from  the  native  sulphuret  solely  in  being  combined  with  water. — 
Gay  Lussac,  however,  maintains  that  it  contains  both  oxide  and  sul- 
phurei  of  antimony. — tfnn.  de  C/dm.  ct  de  Phys.  xlii.  88,  or  Phil.  Mag. 
and  Ann.  vii.  386.  Berzclins,  Traite  dc  Chim. 

Bisulpkuret  of  Antimony. — Atom.  Num.  9G-6 — SywJo.  2 
S+Sb. 

This  compound  is  formed,  according  to  Rose,  by  transmitting  sul- 
phuretted hydrogen  gas  through  a  solution  of  the  deutoxide  of  anti- 
mony in  dilute  muriatic  acid. 


ANTIMONY.  317 

Per  sulphuret  of  Antimony. — Atom.  Num.   104 '6 — Symb.  2J 
S+Sb. 

This  compound  is  formed  by  the  action  of  sulphuretted  hydrogen 
on  a  solution  of  the  peroxide,  and  is  identical  with  the  golden  sul- 
phuret  prepared  by  boiling  sulphuret  of  antimony  and  sulphur,  in  so- 
lution of  potassa. 

M.  Rose  has  likewise  demonstrated,  that  the  Red  Antimony  of  min- 
eralogists, is  a  compound  of  one  proportion  of  the  protoxide,  combin- 
ed with  two  proportions  of  the  sequisulphuret  of  antimony.  The 
pharmaceutic  preparations  known  by  the  terms  of  Glass,  Liver,  and 
Crocus  of  antimony,  are  of  a  similar  nature,  though  less  definite  in 
composition,  owing  to  the  mode  by  which  they  are  prepared.  They 
are  made  by  roasting  the  native  sulphuret,  so  as  to  form  sulphurous 
acid  and  oxide  of  antimony,  and  then  vitrifying  the  oxide  together  with 
the  undecomposed  ore,  by  means  of  a  strong  heat.  The  product  will 
of  course  differ  according  as  more  or  less  of  the  sulphuret  escapes  ox- 
idation during  the  process. — Turner. 

ANTIMONY  AND  THE  METALS. 

Antimony  may  be  made  to  combine  with  nearly  all  the  metals.  The 
most  important  of  these  alloys,  is  that  which  it  forms  with  lead,  called 
Type  Metal.  The  composition  of  this  alloy  varies  ;  the  smallest  types, 
Mr.  Dalton  finds,  are  cast  from  an  alloy  composed  of  nearly  one  atom 
of  antimony  to  one  of  lead  ;  middle  sized  types  of  a  compound  of  one 
atom  of  antimony  and  two  of  lead  ;  and  the  largest  size  of  one  atom 
of  antimony  and  three  of  lead. — New  System. 

Antimony  may  also  be  alloyed  with  tin,  but  if  its  proportion  in  the 
alloy  exceeds  one-fourth,  the  tin  loses  its  ductility. 

The  alloy  of  one  part  of  antimony  and  two  parts  of  iron  deserves 
notice,  for  the  singular  property  which  it  possesses  of  giving  fire  when 
acted  on  by  the  file, — T/ienard,  i.  644. 

The  alloy  of  antimony  and  gold  is  remarkable  in  being  brittle  when 
it  contains  only  a  minute  proportion  of  antimony.  According  to 
Hatchett.  gold  loses  its  ductility  by  combination  with  l-1920ths  of  its 
weight  of  antimony. 

SALTS  OF  ANTIMONY. 

Antimony  is  soluble  in  most  of  the  acids.  When  heated  with  Sul- 
phuric Acid,  the  acid  is  decomposed  ;  sulphurous  acid  is  disengaged, 
and  the  antimony  being  converted  into  protoxide,  a  subsulphate  is  the 
product.  Nitric  Acid  dissolves  this  metal  with  great  vehemence  ;  but 
the  most  convenient  solvent  is  the  nitre-muriatic  acid,  which  acts 
upon  the  metal  both  in  a  separate  state,  and  as  it  exists  in  the  black 
sulphuret.  Muriatic  Acid  acts  on  the  latter  compoun^  and  evolves 
sulphuretted  hydrogen  gas  in  abundance,  and  of  great  purity  ;  and 
muriate  of  ammonia  is  also  lormed,  and  remains  in  solution  along  with 
the  muriate  of  antimony. — Berztlius,  Ann.  de  Chim.  el  de  Phys.  xviL 
Henry,  ii.  85. 

Phosphate  of  Antimony — has  not  been  examined.  The  medicinal 
preparation  called  James'  Powder,  was  found  by  Dr.  Pearson  to  con- 
sist of  57  oxide  of  antimony,  and  43  phosphate  of  lime  ,•  and  it  has 

u 


318  URANIUM. 

been  imitated  in  the  Pulvis  Antimonialis  of  the  London  Pharmacopeia, 
which  is  formed  by  calcining  the  native  sulphuret  with  hartshorn 
shavings.  The  preparation  appears  to  be  uncertain  and  often  even 
almost  inert,  and  to  vary  as  to  the  state  of  oxidation  in  the  antimony, 
containing  sometimes  a  large  proportion  of  the  peroxide. 

REFERENCES.  Pearson,  in  Phil.  Trans.  171)1.  R.  Phillips,  in  Ann.  of 
Phil.  xx.  266,  xxii.  187.  Webster's  Brande. 

Tartarized  Antimony,  or  Emetic  Tartar,  is  a  triple  salt  of  protoxide  of 
antimony,  potassa  and  tartaric  acid,  which  will  be  noticed  under  the 
head  of  the  Tartrates. 

The  rfniimonites  and  Antimoniates,  are,  in  general,  soluble  in  water, 
and  easily  decomposable  by  sulphuric,  nitric  and  muriatic  acids. — 
Those  of  potassa,  soda  and  ammonia,  are  obtained  directly  ;  all  the 
others  by  double  decomposition.  Most  of  these  compounds,  when 
heated  strongly  in  a  platinum  crucible,  burn  with  evolution  of  light 
and  heat ;  this  is  especially  the  case  with  the  antimonite  and  antinio- 
niate  of  copper  and  of  cobalt.  Berzelius  attributes  this  singular  phe- 
nomenon to  the  more  intimate  union  of  the  molecules  of  these  com- 
pounds ;  for  he  observes,  that,  after  the  calcination,  the  antimonites 
and  antimoniates  are  with  difficulty  acted  on,  even  by  the  strongest 
acids.  Gay  Lussac,  however,  dissents  from  this  opinion. 

REFERENCES.  Thenard,  Traite  de  Cliim.  iii.  459.  Berzelins,  in  Ann.  de 
Chim.  Ixxxvi.  225.  Gay  Lussac,  Ann  de  Chim.  et  de  Phys.  i.  44,  and,  same 
work,  v.  158,  160.  And  for  further  details  concerning  the  properties  of  these 
saline  compounds,  see  Beizelins,  in  Ann.  de  Chim.  et  de  Phys.  xvii.  1G. 

SECTION  XXVII. 
URANIUM. 

Atom.  Num.  2i7—Symb.  U. 

Discovered  by  Klaproth,  in  1789,  in  a  mineral  of  Saxony,  called 
from  its  black  colour,  Pitchblende,  which  consists  of  protoxide  of  ura- 
nium and  oxide  of  iron.  It  is  a  rare  metal,  and  still  imperfectly 
known. 

PROPERTIES.  This  metal,  as  prepared  by  Arfwedson,  by  conduct- 
ing hydrogen  gas  over  protoxide  of  uranium,  heated  in  a  glass  tube, 
is  crystalline,  of  a  metallic  lustre  and  reddish-brown  colour  ;  it  is  not 
changed  by  exposure  to  the  air  at  common  temperatures,  but  when 
heated  in  open  vessels  absorbs  oxygen,  and  is  re-converted  into  the 
protoxide. 

PREPARATION.  Metallic  uranium  may  be  obtained  from  the  pitch- 
blende by  the  following  process  :  reduce  it  to  powder  and  expose  it  to 
heat  in  a  muffle  ;  then  digest  in  dilute  nitro  muriatic  acid,  and  precip- 
itate by  excess  of  ammonia,  to  retain  oxide  of  copper  ;  collect  and 
wash  the  precipitate  and  dry  it  at  a  heat  approaching  redness. 

REFERENCES.  For  the  details  of  this  process,  see  Arficedson's  paper  on 
Uranium,  in  Ann.  of  Phil,  xxiii.  253.  For  the  process  of  Dr.  Thomson,  see 
his  First  Prin.  ii.  2.  On  Uranium  and  its  compounds,  see  also  the  Memoir 
of  Bucholz,  in  Gehlen's  Jour,  or  Repert.  of  Arts,  2d  ser.  viii.  294. 


URANIUM.  319 

URANIUM  AND  OYYGEN. 

Chemists  are  acquainted  with  two  compounds  of  uranium  and  oxy- 
gen, the  Protoxide  and  the  Peroxide. 

Protoxide  of  Uranium. — Jltom.  Num.  225 — Symb.  G-fU. 

PROPERTIES.  A  compound  of  a  dark  green  colour,  which  is  exceed- 
ingly infusible,  and  bears  any  temperature  hitherto  tried,  without 
change  ;  it  unites  with  acids,  forming  salts  of  a  green  colour  ;  by  the 
action  of  nitric  acid  it  is  converted  into  a  solution,  which  is  the  nitrate 
of  the  protoxide. 

This  oxide  is  obtained  by  decomposing  the  nitrate  of  the  peroxide 
by  heat.  It  is  employed  in  the  arts  for  giving  a  black  colour  to  porce- 
lain. 

Peroxide  of  Uranium. — Atom.  Num.  229 — Symb.  ]£  O+U. 

PROPERTIES.  This  oxide  is  of  a  yellow  or  orange  colour,  and  per- 
forms, as  was  first  noticed  by  Arfwedson,  the  double  function  of  acid 
and  base  ;  it  is  precipitated  from  acids  as  a  yellow  hydrate  by  pure 
alkalies,  fixed  or  volatile,  but  retains  a  portion  of  these  bases  in  com- 
bination ;  it  is  thrown  down  as  a  carbonate  by  the  carbonate  of  soda 
or  ammonia,  and  is  re-dissolved  by  an  excess  of  the  precipitant,  a  cir- 
cumstance which  affords  an  easy  method  of  separating  uranium  from 
iron.  It  is  employed  in  the  arts  for  giving  an  orange  colour  to  porce- 
lain. 

URANIUM  AND  SULPHUR. 

Sulphur d  of  Uranium,  may  be  formed  according  to  Rose  by  trans- 
mitting the  vapour  of  bisulphuret  of  carbon  over  protoxide  of  uranium 
strongly  heated  in  a  tube  of  porcelain.  It  is  of  a  dark  gray,  or  nearly 
black  colour,  is  converted  into  protoxide  of  uranium  when  heated  in 
the  open  air,  and  is  readily  dissolved  by  nitric  acid. 

SALTS  OF  URANIUM. 

It  is  difficult  to  obtain  the  protosalts  of  this  metal  pure,  in  conse- 
quence of  the  tendency  of  the  protoxide  to  pass  to  the  state  of  perox- 
ide. The  green  solutions  of  the  former,  by  the  action  of  sulphuric 
and  muriatic  acids,  become  speedily  yellowish,  green  and  yellow,  in 
consequence  of  the  formation  of  peroxide,  arid  the  change  is  accele- 
rated by  adding  a  little  nitric  acid. 

The  Pernitrate  of  Uranium,  is  formed  by  dissolving  the  protoxide 
in  nitric  acid,  and  from  this  solution  the  Percarbonate  is  thrown  down 
by  carbonate  of  ammonia.  The  pernitrate  crystallizes  easily,  in  large 
flat  four-sided  rectangular  prisms,  of  a  lemon  yellow  colour.  The 
Persulphate  appears  to  have  a  similar  constitution  to  the  above  ;  both 

consisting  of  1  1-2  proportion  of  acid,  and  1  proportion  of  base. 

They  are,  therefore,  sesqui-salts.  Indeed,  as  Dr.  Thomson  remarks 
the  tendency  which  peroxide  of  uranium  has  to  form  sesqui-salts  is 
very  remarkable, — First  Prin.  ii.  40. 


320  COLUMBIUM. 

Among  the  native  compounds  of  uranium,,  may  be  mentioned  the 
Green  arid  the  Yelloio  Uran-mica ;  and  the  Protosulphate  and  Sub-per- 
sulphate,  discovered  by  Dr.  John. 

SECTION  XXVIII. 
COLUMBIUM. 

Atom.  Num.  185?— Symb.  Cb. 

This  metal  was  discovered  in  1801,  by  Mr.  Hatchett,  who  detected 
it  in  a  black  mineral,  supposed  to  have  come  from  the  United  States, 
and,  from  this  circumstance,  applied  to  it  the  name  of  Colunibium. 
About  two  years  after,  M.  Ekeberg,  a  Swedish  chemist,  extracted  the 
same  substance  from  Tantalite  and  Yttro-tantalite ;  and,  on  the  suppo- 
sition of  its  being  different  from  columbium,  described  it  under  the 
name  of  Tantalum.  The  identity  of  these  metals,  however,  was  es- 
tablished in  the  year  1809,  by  Dr.  Wollaston.— Phil.  Trans. 

PROPERTIES.  This  metal,  as  prepared  by  Berzelius  by  heating  po- 
tassium with  the  double  fluoride  of  potassium  and  columbium,  is  a 
black  powder,  which  does  not  conduct  electricity,  but  in  a  denser  state 
is  a  perfect  conductor  ;  it  does  not  melt  at  the  temperature  at  which 
glass  is  fused  ;  by  pressure  it  acquires  a  metallic  lustre,  and  has  an 
iron-gray  colour  ;  it  is  scarcely  acted  on  by  the  sulphuric,  muriatic  or 
nitro-muriatic  acid,  but  is  dissolved  with  heat  and  disengagement  of 
hydrogen  gas  by  hydrofluoric  acid,  and  still  more  easily  by  a  mixture 
of  nitric  and  hydrofluoric  acids  ;  when  heated  in  open  air,  it  takes  fire, 
and  is  converted  into  columbic  acid. — Berzelius,  ii.  515,  under  the  name, 
of  Tantalum. 

COLUMBIUM  AND  OXYGEN. 

These  bodies  combine  in  two  proportions,  forming  an  oxide  and  an 
acid. 

Oxide  of  Columbium.— Atom.  Num.  201  ?—Symb.  2O+Cb. 

This  oxide  is  generated  by  placing  columbic  acid  in  a  crucible  lined 
with  charcoal,  luting  carefully  to  exclude  atmospheric  air,  and  expos- 
ing it  for  an  hour  and  a  half  to  intense  heat.  The  acid,  where  in  di- 
rect contact  with  charcoal,  is  entirely  reduced  ;  but  the  film  of  metal 
is  very  thin.  The  interior  portions  are  pure  oxide,  of  a  dark  gray 
colour,  very  hard  and  coherent.  When  reduced  to  powder  its  colour 
is  dark-brown.  It  is  not  attacked  by  any  acid,  even  by  nitro-hydro- 
fluoric  acid ;  but  it  is  converted  into  columbic  acid,  either  by  fusion 
with  hydrate  of  potassa,  or  deflagration  with  nitre.  According  to  Ber- 
zellus  this  oxide  occurs  in  combination  with  protoxide  of  iron  and  a 
little  protoxide  of  manganese,  at  Kimito,  in  Finland, — Traite  de  Chim. 
ii.  527. 

Columbic  Add— Atom.  Num.  209  ?—Symb.  3O+Cb. 

PROPERTIES.     This  acid,  as  obtained  in  the  form  of  hydrate  by  fus 
ing  yttro-tantalite  with  three  or  four  times  its  weight  of  carbonate  of 


CERIUM.  321 

potassa,  and  precipitating  by  acids,  is  tasteless  and  insoluble  in  water, 
but  when  placed  on  litmus  paper  communicates  a  red  tinge  ;  it  is  so- 
luble in  many  of  the  acids,  but  does  not  diminish  their  acidity  ;  it  unites 
readily  with  alkalies  ;  and  though  it  does  not  neutralize  their  proper- 
ties completely,  crystallized  salts  may  be  obtained  by  evaporation,  call- 
ed Columbates;  on  applying  heat  to  the  hydrated  acid,  water  is  expell- 
ed, and  the  anhydrous  cQlumbic  acid  remains., 

REFERENCES.  Thomson's  First  Prin.  ii.  74.  JBerzelius,  as  above.  The 
former  chemist  adopts  a  different  view  of  the  atomic  constitution  of  these  com- 
pounds from  that  entertained  by  the  latter. 

Chloride  of  Columbium., — Columbium  burns  vividly  in  chlorine  gas, 
and  yields  a  yellow  vapour,  which  -condenses  into  a  yellowish-white 
powder.  This,  by  contact  with  water,  is  converted  with  a  hissing 
noise,  into  columbic  and  muriatic  acids. 

Fluocolumbic  Acid,  is  prepared  by  pouring  hydrofluoric  acid  upon  the 
columbic.  It  forms  with  bases,  salts  called  Flnocolumbates. 

Sulphuret  of  Columbium. — Rose  first  prepared  this  substance  by 
Seating  columbium,  at  a  low  redness,  in  the  vapour  of  sulphur,  or  by 
transmitting  the  vapour  of  bisulphuret  of  carbon  over  columbic  acid, 
in  a  porcelain  tube  heated  to  whiteness. 


SECTION  XXIX. 

CERIUM. 

Atom.  Nam.  46. — Symb.  Ce. 

This  metal  was  discovered  in  1803,  by  Berzelius  and  Hisinger,  in  a 
i-are  Swedish  mineral,  called  Cerite.  It  has  since  been  found,  by  Dr. 
Thomson,  in  a  mineral  from  Greenland,  called  Allanile.  It  is  but  lit- 
tle known. 

PROPERTIES.  A  solid,  very  brittle  metal,  of  a  whitish  colour,  and 
almost  infusible  ;  when  heated  to  redness  in  the  open  air  it  is  convert- 
ed into  a  white  oxide,  and  when  heated  intensely  it  is  volatile  ;  it  is 
acted  upon  by  nitro-muriatic  acid. 

Cerium  may  be  obtained  by  subjecting  its  oxide  to  a  high  heat  in 
combination  with  charcoaL 

CERIUM    AND    OXYGEN. 

There  are  two  oxides  of  cerium,  which  have  been  studied  by  Hisin- 
ger, Vauquelin  and  Thomson. 

Protoxide  of  Cerium. — Atom.  Num.  54 — Symb.  O-j-Ce. 

PROPERTIES.  A  white  powder,  which  is  insoluble  in  water,  and 
forms  salts  with  acids  ;  it  undergoes  no  change  by  exposure  to  air  at 
common  temperatures,  but  when  heated  in  open  vessels  it  absorbs  oxy- 
gen, and  is  converted  into  the  peroxide. 


TITANIUM. 

PREPARATION.  This  oxide  is  obtained  by  3 
der,  and  dissolving  it  in  nitro-muriatic  acid.  The  solution  is  filtered, 
neutralized  with  pure  potassa,  and  then  precipitated  by  tartrate  of 
potassa  ;  or,  as  Langier  recommends,  by  oxalic  acid.  This  precipitate, 
well  washed  and  afterwards  calcined,  is  the  protoxide  of  cerium. 

Peroxide  of  Cerium. — Atom.  Num.  58 — Symb.  IJO+Ce. 

This  oxide  is  of  a  fawn-red  colour  ;  it  is  dissolved  by  several  of  the 
acids,  but  is  a  weaker  base  than  the  protoxide.  It  is  obtained  by  de- 
composing the  nitrate  of  the  protoxide,  or  by  heating  the  carbonate 
to  redness  in  the  open  air. 

REFERENCES.  Hisingeron  the  Oxides  of  Cerium^  Ann.  of  Phil.  iv.  355. 
Thomson's  First  Priu.  i.  37S>. 


CERIUM   AND    SULPHUR. 

Cerium  may  be  combined  with  sulphur  in  two  different  ways.  1.  By 
passing  the  vapour  of  carburet  of  sulphur  over  carburet  of  cerium,  a 
light  porous  compound  is  obtained,  of  the  colour  of  minium,  which 
is  not  altered  either  by  air  or  water.  2.  By  fusing  oxide  of  cerium 
with  a  great  excess  of  sulphuret  of  potassium,  (hepar  sulphvris,)  the 
latter  of  which  is  removed  by  washing. — Mosander,  in  Phil.  Mag.  and 
Ann.  i.  71. 

Berzelius  describes  compounds  of  phosphorus,  carbon  and  selenium, 
with  cerium. — Traite  de  Chim.  iii.  315. 

SALTS    OF    CERIUM. 

Permuriate  of  Cerium,  crystallizes  confusedly  ;  is  deliquescent,  so- 
luble in  an  equal  weight  of  water,  and  in  three  or  four  parts  of  alco- 
hol. 

Nitric  acid  unites  most  easily  with  the  white  oxide.  The  solution 
is  very  sweet,  and  is  not  crystallizable.  When  decomposed  by  heat  it 
leaves  a  brick-coloured  oxide. 

Protosulphate  of  Cerium,  occurs  in  white  crystals,  of  a  saccharine 
taste.  It  is  formed  by  the  action  of  sulphuric  acid  upon  the  white  ox- 
ide. There  is  also  a  Persulphate. 

Carbonate  of  Cerium,  is  a  white  powder,  which  assumes  on  drying  a 
silvery  appearance. 

SECTION  XXX. 

TITANIUM. 

Atom.  Mm.  24-3— Symb.  Ti.—Sp.  gr.  5  3. 

This  was  first  recognized  as  a  new  metal  by  Mr.  Gregor,  of  Corn- 
wall,  in  1791,  and  its  existence  was  afterwards  established  by  Klap- 
roth.  Its  properties,  however,  were  first  satisfactorily  ascertained  by 


TITANIUM.  323 

Dr.  Wollaston,  in  1822,  who  found  the  native  metal  in  a  crystalline 
form. 

PROPERTIES.  Native  titanium  occurs  in  cubic  crystals,  whose  colour 
and  lustre  are  like  burnished  copper  ;  it  is  so  hard  as  to  scratch  rock 
crystal ;  is  exceedingly  infusible,  but  when  exposed  to  the  united  ac- 
tion of  heat  and  air,  the  surface  becomes  covered  with  a  purple  film, 
which  is  an  oxide  ;  it  is  oxidized  by  being  strongly  heated  with  nitre. 

PREPARATION.  Liebig  obtains  metallic  titanium  by  putting  frag- 
ments of  recently  made  chloride  of  titanium  and  ammonia  in  a  glass 
tube  half  an  inch  wide  and  two  or  three  feet  long,  transmitting  through 
it  a  current  of  perfectly  dry  ammonia,  and  when  atmospheric  air  is  en- 
tirely displaced,  applying  heat  until  the  glass  softens.  Complete  de- 
composition ensues,  nitrogen  gas  is  disengaged,  muriate  of  ammonia 
sublimes,  and  metallic  titanium  is  left  in  the  state  of  a  deep  blue  co- 
loured powder.  If  exposed  to  the  air  while  warm,  it  is  apt  to  take 
fire. 

REFERENCES.  Klaproth'*  Contribution,  i.  Wollaston,  in  Phil.  Trans, 
for  1823. 

TITANIUM    AND    OXYGEN. 

Titanium  most  probably  combines  in  two  proportions  with  oxygen. 

Protoxide  of  Titanium  is  of  a  purple  colour,  and  is  supposed  to  exist 
pure  in  the  mineral  called  Anatase;  but  its  composition  and  chemic- 
al properties  are  unknown. 

Titanic  Add.— Atom.  Num.  40-3—  Symb.  2O+T1. 

PROPERTIES.  When  pure  this  substance  is  quite  white  ;  it  is  ex- 
ceedingly infusible,  and  difficult  of  reduction  ;  possesses  weak  acid 
properties,  and  according  to  Rose  does  not  act  as  a  base ;  after  expo- 
sure to  a  red  heat  it  is  not  attacked  by  any  acid  except  the  hydro- 
fluoric. 

NATIVE  STATE  AND  PREPARATION.  Titanic  acid,  or  the  peroxide  of 
titanium,  exists  in  nearly  a  pure  state  in  the  Titanite  or  Rutile.  From 
this  mineral  titanic  acid  is  prepared  by  fusion  with  carbonate  of  po- 
tassa,  dissolving  the  mass  in  concentrated  muriatic  acid,  throwing 
down  the  oxide  by  dilution  with  water,  and  boiling  ;  and  finally,  se- 
parating the  impurities  by  digesting  the  precipitate  while  moist,  with 
hydrosulphuret  of  ammonia. 

REFERENCES.  Rose  in  Ann.  de  Chim.  et  de  Phys.  xxiii.  For  other  pro- 
cesses, see  Berzelius,  ii.  538 ;  and  Rose's  Manual  of  Analytical  Chemistry. 

TITANIUM    AND    CHLORINE- 

Bichloride  of  Titanium,  was  formed  by  Mr.  George  by  passing  dry 
chlorine  over  the  pulverized  native  metal.  A  fluid  condensed  in  the 
cool  part  of  the  tube,  which  was  transparent,  colourless,  emitted  dense 
white  fumes,  arid  boiled  violently  at  a  temperature  little  exceeding 
212J  F.  On  adding  a  drop  of  water  to  a  few  drops  of  this  liquid,  an 
almost  explosive  disengagement  of  chlorine  ensued  ;  and  when  the 


324  TELLURIUM. 

water  was  not  in  excess,  a  solid  salt  was  formed,  the  solution  of  which 
had  all  the  properties  of  Muriate  of  Titanium.  Rose  prepared  this  com- 
pound by  heating  a  mixture  of  the  peroxide  and  charcoal  in  a  tube, 
through  which  dry  chlorine  gas  was  passing:  the  resulting  bichloride  was 
purified  from  adhering  to  free  chlorine  by  agitation  either  with  mercury 
or  potassium  and  repeated  distillation. — Ann.  of  Phil.  xxv.  18. 

TITANIUM    AND    SULPHUR. 

Eisulphuret  of  Titanium,  was  formed  by  Rose,  by  passing  sulphuret 
of  carbon  over  titanic  acid,  strongly  heated  in  a  porcelain  tube.  It  is 
of  a  deep  green  colour,  and  when  rubbed  with  a  hard  substance,  as- 
sumes a  very  strong  metallic  lustre  like  that  of  brass.  It  becomes 
very  hot  when  nitric  acid  is  poured  upon  it ;  nitrous  gas  is  disengaged 
and  titanic  acid  is  deposited  in  the  state  of  a  fine  powder. 

SECTION  XXXI. 

TELLURIUM. 
• 

Atom.  Num.  61 — Symb.  Te.—  Sp.  gr.  6-245.  Btrzelius. 

A  very  rare  metal,  hitherto  found  only  in  the  gold  mines  of  Tran- 
sylvania, and  even  there  in  very  small  quantity.  Its  existence  was 
inferred  by  Muller,  in  1782,  and  fully  established  by  Klaproth,  in 
1798. 

PROPERTIES.  Tellurium  has  a  tin-white  colour,  running  into  lead* 
gray,  a  strong  metallic  lustre,  and  laminated  texture  ;  it  is  very  brit- 
tle ;  when  heated  to  full  redness  in  a  close  vessel  it  volatilizes  in  the 
form  of  a  yellow  gas,  which  condenses  again  in  drops,  and  on  cooling 
crystallizes  in  regular  forms  ;  is,  fusible  at  a  temperature  below  ignition; 
when  heated  before  the  blow-pipe  it  takes  fire  and  burns  rapidly,  and  is 
dissipated  in  gray  coloured  pungent  inodorous  fumes. 

TELLURIUM    AND    OXYGEN. 

Berzeliushas  obtained  two  compounds  of  tellurium  and  oxygen,  both 
of  which  possess  acid  properties. 

TeUurous  Acid.— Atom.  Num.  80—Symb.  2O+Te. 

When  tellurium  is  exposed  to  the  action  of  the  blow-pipe  upon  char- 
coal, it  takes  fire,  and  burns  with  a  lively  blue  flame,  the  edges  of 
which  are  green  ;  and  it  is  completely  volatilized  in  the  form  of  a  white 
smoke.  This  smoke  is  the  tellurous  acid,  which  may  also  be  obtained 
by  dissolving  the  metal  in  nitro-muriatic  acid,  and  diluting  the  solution 
with  a  great  quantity  of  water.  It  is  fusible  at  a  strong  heat,  and  vol- 
atile at  a  still  higher  temperature.  It  forms  a  class  of  salts  called  Td~ 
lurites;  and  can  scarcely  be  made  to  act  as  a  base. 


TELLURIUM.  325 

Telluric  Acid.— Atom.   Num.  SS—Symb.  3O-f-Te. 

This  acid  is  obtained,  according  to  Berzelius  by  submitting  the  tel- 
iurous  acid  in  solution  with  excess  of  caustic  alkali  to  a  current  of  chlo- 
rine, till  the  precipitate  which  at  first  falls,  is  entirely  redissolved. 
Chloride  of  barium  is  added  to  precipitate  any  sulphuric  or  selenic 
acid  which  may  be  present,  after  which  the  solution  is  saturated  with 
ammonia,  and  the  tellurate  of  barytes  precipitated  by  chloride  of  ba- 
rium, collected  and  washed  with  cold  water.  This  salt  is  decomposed 
by  sulphuric  acid,  and  the  concentrated  solution  deposites  the  telluric 
acid  in  beautiful  crystals. — [For  details  concerning  this  and  the  pre- 
ceding acid,  see  a  notice  of  the  recent  researches  of  Berzelius  in  Johns- 
ton's  Report  on  Chemistry. ~\ 

TELLURIUM    AND    CHLORINE. 

Chlorides  of  Tellurium.— These  have  been  recently  examined  by 
Rose.  When  the  metal  is  gently  heated  in  chlorine  gas,  a  white  crys- 
talline compound  is  formed,  consisting  of  two  atoms  chlorine-f-  one 
atom  tellurium.  It  has  much  resemblance  to  the  solid  chloride  of  se- 
lenium. When  the  metal  is  strongly  heated  in  the  same  gas,  violet  va- 
pours are  formed,  which  condense  into  a  black  deliquescent  mass. 
When  freed  as  much  as  possible  from  bichloride,  this  substance  was 
found  to  consist  of  one  atom  chlorine-j-one  atom  tellurium. 

TELLURIUM  AND  HYDROGEN. 

Tellurctted  Hydrogen. — A  gaseous  substance  discovered  by  Sir  H. 
Davy,  in  1809.  It  is  colourless,  has  an  odour  similar  to  that  of  sul- 
phuretted hydrogen,  and  is  absorbed  by  water,  forming  a  claret  colour- 
ed solution.  As  it  unites  with  alkalies  it  may  be  regarded  as  a  feeble 
acid.  It  reddens  litmus  paper  at  first,  but  loses  this  property  after  be- 
ing washed  with  water. 

Berzelius  also  describes  compounds  of  sulphur,  selenium,  aluminum 
and  glucinum  with  tellurium. — Traite  de  Chim.  ii.  520.  Johnston's 
Roport. 


326  BISMUTH. 

CLASS  V. 
ORDER  II. 

METALS    WHICH    DO    NOT    FORM    ACIDS. 

SECTION  XXXII. 
BISMUTH. 

Atom.  Num.  7l.—Symb.  Bi.— %  gr.  9.822. 

This  metal  was  known  as  early  as  1520  ;  but  the  first  satisfactory 
account  of  it  was  published  by  Geoffry,  in  1723. 

PROPERTIES.  Bismuth  has  a  reddish  white  colour  and  considerable 
lustre  ;  its  structure  is  highly  lamellated.  and  when  slowly  cooled  it 
crystallizes  in  octahedrons  ;  it  is  brittle  when  cold,  but  may  be  ham- 
mered into  plates  while  warm;  fuses  at  476°  F.*  and  sublimes  in  close 
vessels  at  about  3(P  of  Wedgewood  ;  is  but  little  changed  by  exposure 
to  air  at  common  temperatures,  but  when  fused  in  open  vessels  it  be- 
comes oxidated,  and  when  heated  to  the  subliming  point,  it  burns 
with  a  bluish-white  flame,  and  emits  copious  fumes  of  the  oxide  of  bis- 
muth. 

NATIVE  STATE  AND  EXTRACTION.  Bismuth  is  rarely  found  native, 
but  it  is  often  met  with  in  combination  with  oxygen,  sulphur  and  arse- 
nic. It  may  be  obtained  pure  for  chemical  purposes,  by  heating  the 
oxide  or  subnitrate  to  redness  along  with  charcoal. 

BISMUTH    AND    OXYGEN. 

These  two  bodies  combine  only  in  one  proportion,  though  Berzelius 
considers  the  film  formed  on  the  surface  of  the  metal,  when  exposed 
to  the  air,  as  a  Subozide. — Traitede  Chim.  iii.  151. 

Oxide  of  Bismuth. — Atom.  Num.  tS—Symb.  O+Bi. 

A  yellow  coloured  powder,  sometimes  called  Flowers  of  Bismuth, 
which,  at  a  full  red  heat,  is  fused,  and  yields  a  transparent  yellow 
glass,  and,  at  a  higher  temperature,  is  sublimed  ;  it  unites  with  acids, 
and  most  of  its  salts  are  white. 


*  Marx  has  ascertained  that  bismuth  at  the  moment  of  solidifying1  expands 
1*53 rd  of  it*  volume.  He  considers  also  that,  like  water,  it  has  in  the  fluid 
state  a  point  of  maximum  density. — Johnston's  Report  on  Chemistry. 


BISMUTH.  327 

This  oxide  is  formed  by  exposing  the  metal  to  heat,  and  air,  or  by 
heating  the  subnitrate  to  redness. 

REFERENCES.  Lijerhielm'i  Experiments  to  determine  the  proportion  in 
which  Bismuth  unites  with  Sulphur  and  Oxygen,  Ann.  of  Phil,  if  ,  357.  Dr. 
Vary,  in  Phil.  Trans,  for  1812.  Thomson's  I'irst  Prin.  i.  407. 

BISMUTH    AND    CHLORINE. 

lorideof  Bismuth.—  titom.  Num.  106-45-—  %?»&.  Cl+Bi. 


A  substance  of  a  grayish-white  colour,  granular  texture,  which  is 
opaque,  and  is  not  sublimed  by  heat  ;  formerly  called  Butter  of  Bis- 
muth. It  may  be  prepared  by  introducing  bismuth,  in  fine  powder, 
into  chlorine  gas  ;  or  by  heating  two  parts  of  corrosive  sublimate  with 
one  of  bismuth,  and  afterwards  expelling  the  excess  of  the  former,  to- 
gether with  metallic  mercury,  by  heat. 

BISMUTH    AND    BROMINE. 

Bromide  of  Bismuth.  —  A  solid,  of  a  steel-gray  colour,  having  the  as- 
pect of  iodine,  fused  into  a  solid  mass.  It  fuses  at  392°  F.  and  then 
assumes  a  hyacinth  red  colour,  but  resumes  its  former  colour  on  cool- 
ing. It  may  be  formed  by  exposing  to  heat  bismuth  in  powder  with  a 
great  excess  of  bromine  in  a/long  tube  shut  at  one  end.  The  bromide 
of  bismuth  is  found  at  the  bottom  of  the  tube.  —  Serullas. 

BISMUTH    AND    IODINE. 

Iodide  of  Bismuth,  may  be  formed  by  heating  that  metal  with  iodine, 
It  is  of  an  orange  colour,  and  insoluble  in  water.  With  hydriodic 

acid,  or  hydriodate  of  potassa,  nitrate  of  bismuth  affords  a  deep  choco- 
late coloured  precipitate. 

BISMUTH    ANE    SULPHUR. 

SuJphuret  of  Bismuth.—  Atom.  Num.  Q7—Symb.  S+Bi. 

Bismuth  combines  readily  with  sulphur  and  forms  a  bluish-gray  sul- 
phuret,  having  a  metallic  lustre.  The  same  compound  is  also  found 
native  in  Cornwall,  Bohemia,  Saxony  and  Sweden. 

BISMUTH    AND    THE    METALS. 

Bismuth  is  capable  of  being  alloyed  with  most  of  the  metals,  and 
forms,  with  some  of  them,  compounds  of  remarkable  fusibility.  One 
of  these  is  Sir  Isaac  Newton's  Fusible  Metal.  It  consists  of  eight  parts 
of  bismuth,  five  of  lead,  of  three  of  tin,  or,  according  to  Dobereiner. 
when  made  in  the  best  proportions,  it  is  a  compound  of  1  atom  of 
lead,  1  of  tin  and  2  atoms  of  bismuth,  or  an  atom  of  the  binary  alloy 


328  BISMUTH. 

of  bismuth  and  lead,  united  with  an  atom  of  the  binary  alloy  of  bis- 
muth and  tan.  [Ann.  of  Phil.  xxv.  389.]  When  thrown  into  water  it 
melts  before  the  water  is  heated  to  the  boiling  point.  It  is  from  the 
property  of  forming  fusible  alloys,  that  bismuth  enters  into  the  compo- 
sition of  several  of  the  soft  solders,  which  indeed,  is  its  principal  use  in 
the  arts. 

Bismuth,  like  antimony,  has  the  singular  property  of  depriving  gold 
of  its  ductility — even  when  combined  with  it  in  very  minute  propor- 
tion. This  effect  is  produced  by  merely  keeping  gold  in  fusion  near 
melted  bismuth.  It  has.  nevertheless,  been  employed,  by  Chaudet,  in 
eupellation. — Ann.  de  Chim.  et  de  Phys.  viii.  113.  Henry,  ii.  107. 


SALTS  OF  BISMUTH. 

Nitrate  of  Bismuth.—  Atom.  Num.  160—  Symb.  (5O+N)+ 

Aq. 


A  transparent  crystalline  salt,  which  is  decomposed  by  water,  a 
white  subnitrate  being  precipitated,  which  is  called  Mogistery  of  Bis- 
muth, or  Pearl  White,  in  which  state  it  is  employed  in  medicine.  The 
solution  is  also  employed  for  forming  a  white  sympathetic  ink. 

It  is  prepared  by  dissolving  bismuth  in  dilute  nitric  acid,  in  the  pro- 
portion of  one  part  of  the  former  to  one  and  a  half  parts  of  the  latter. 
The  bismuth  is  to  be  broken  into  small  pieces  and  added  at  distant  in- 
tervals. 

The  subnitrate  of  bismuth,  in  large  doses,  is  an  active  poison.  —  See 
Christison.  371. 

Sulphate  of  Bismuth.—  Atom.  Num.  119—  Symb.  (3O+S)+ 
(0+Bi.) 

This  salt  occurs  in  the  form  of  a  white  powder,  or  in  needles  ;  it 
is  insoluble  in  water,  but  is  decomposed  by  it,  and  converted  into  a 
Subsulphate  and  Super  sulphate.  [Webster's  Erande.~\  It  is  formed  by 
the  action  of  hot  and  concentrated  sulphuric  acid  upon  metallic  bis- 
muth. 

Carbonate  of  Bismuth.—  Atom.  Num.  277—  Symb.  (2O+C)+ 
(30+Bi.)+2Aq. 

A  white  tasteless  powder,  quite  insoluble  in  water  ;  formed  by  de- 
composing nitrate  of  bismuth  by  an  alkaline  carbonate. 

REFERENCES.  For  description  of  several  other  Sails  of  Bismuth,  see 
Thomson's  First  Prin.  ii.  389,  and  Inorg.  Chem. 

TESTS    OF  THE   SALTS    OF    BISMUTH. 

Water  poured  into  a  colourless  solution  of  these  salts,  produces  a 
white  precipitate.  Gallic  acid  occasions  an  orange  yellow,  and  ferro- 
cyanate  of  potassa  a  yellowish  precipitate. 


COPPER.  329 

SECTION  XXXIH. 

COPPER. 

Atom.  Num.  31-5  —  Symb.  Cu.  Sp.  *gr.  8-695. 
This  metal  was  known  in  the  earliest  ages  of  the  world. 

PROPERTIES.  Copper  is  distinguished  from  all  other  metals,  titani- 
um excepted,  by  having  a  red  colour  ;  it  receives  a  considerable  lustre 
by  polishing;  it  is  both  ductile  and  malleable,  and,  in  tenacity,  is  in- 
ferior only  to  iron  ;  it  is  hard  and  elastic,  and  consequently  sonorous  ; 
in  fusibility  it  stands  between  silver  and  gold  ;  it  undergoes  little 
change  in  a  perfectly  dry  atmosphere,  but  is  rusted  in  a  short  time  by 
exposure  to  air  and  moisture,  being  converted  into  a  green  substance, 
the  carbonate  of  the  black  oxide  of  copper  ;  at  a  red  heat  it  absorb* 
oxygen,  and  is  converted  into  the  oxide,  which  appears  in  the  form 
of  black  scales. 

NATIVE  STATE  AND  EXTRACTION.  Native  copper  is  by  no  means  un- 
common. It  occurs  in  large  amorphous  masses  in  the  northwestern 
parts  of  this  continent,  and  is  sometimes  found  in  octahedral  crystals, 
or  in  forms  allied  to  the  octahedron.  It  also  occurs  in  various  states 
of  combination,  as  the  oxide,  chloride,  sulphuret,  &c.  Perfectly  pure 
copper  may  be  obtained  by  dissolving  the  copper  of  commerce  in  muri- 
atic acid  ;  the  solution  is  diluted  and  a  plate  of  iron  immersed,  upon 
which  the  copper  is  precipitated.  It  may  be  fused  into  a  button,  after 
having  been  previously  washed  in  dilute  sulphuric  acid  to  separate  a 
little  iron  that  adheres  to  it. 

REFERENCES.  For  localities  of  Native  Copper,  see  Cleaveland's  Mineral- 
ogy.  Vauquelin  on  precipitating  Copper  by  Iron  and  Zinc,  Ann.  de  Chiin. 
Ixxxvii.  16,  or  Ann.  of  Phil.  iv.  157.  Dr.  Cooper  on  the  reduction,  SfC.  of 
the  Ores  of  Copper,  Emporium  of  Arts,  ii.  215.  An  article  'on  Mining  iu 
Copper  and  Tm  in  Cornwall,  in  the  Quarterly  Review,  xxxvi.  31. 

COPPER    AND    OXYGEN. 

Three  distinct  oxides  of  copper  are  now  recognized  by  chemists. 

Red  or  Suboxide  of  Copper.  —  Atom.  Num.  71*2  —  Symb. 


PROPERTIES.  Orange  yellow,  in  the  state  of  hydrate,  red  when  pure; 
fusible,  below  a  red  heat,  into  a  reddish  mass  ;  absorbs  oxygen  gas  at  a 
temperature  slightly  elevated  and  passes  into  the  state  of  oxide  ;  it 
forms  a  colourless  solution  with  ammonia,  which  becomes  blue  by  ex- 
posure to  the  air. 

*  From  the  latin  Cuprum. 


330  COPPER. 

NATIVE  STATE  AND  PREPARATION.  This  oxide  occurs  native  in  the 
form  of  octahedral  crystals,  and  is  found,  of  peculiar  beauty,  in  the 
mines  of  Cornwall.  It  may  be  prepared  artificially  by  heating  in  a  co- 
vered crucible  a  mixture  of  31-6  parts  of  copper  filings  with  39-6  of  the 
black  oxide  ;  or  still  better  by  arranging  thin  copper  plates  one  above 
the  other  with  interposed  strata  of  the  black  oxide,  and  exposing  them  to 
a  red  heat  carefully  protected  from  the  air.  It  may  also  be  obtained  by 
boiling  a  solution  of  the  acetate  of  copper  with  sugar,  when  the  suboxide 
subsides  as  a  red  powder. 

Black  or  Protoxide  of  Copper. — Atom.  JYum.  39.6 — Symb, 
O+Cu. 

PROPERTIES.  Colour  varying  from  a  dark  brown  to  a  bluish  black3 
according  to  the  mode  of  formation  ;  undergoes  no  change  by  heat 
alone,  but  is  readily  reduced  to  the  metallic  state  by  heat  and  combus- 
tible matter  ;  is  soluble  in  ammonia,  forming  with  it  a  deep  blue  solu- 
tion, by  which  it  is  distinguished  from  all  other  substances. 

NATIVE  STATE  AND  PREPARATION.  This  oxide  of  copper,  the  Cop- 
per Black  of  mineralogists,  is  sometimes  found  native,  being  formed 
by  the  spontaneous  oxidation  of  other  ores  of  copper.  It  may  be  pre- 
pared artificially,  by  calcining  metallic  copper,  by  precipitation  from 
the  salts  of  copper  by  means  of  pure  potas^a,  and  by  heating  the  ni 
trate  of  copper  to  redness. 

Peroxide  of  Copper. — Atom.  Num.  47'6 — Symb.  2O+Cu. 

This  oxide  was  prepared  by  Thenard  by  the  action  of  peroxide  of  hy- 
drogen diluted  with  water  on  the  hydrated  black  oxide.  It  suffers 
spontaneous  decomposition  under  water  ;  but  it  may  be  dried  in  vacuo 
by  means  of  sulphuric  acid.  When  thrown  upon  a  red  hot  coal  it 
detonates,  and  the  copper  is  reduced.  It  is  insoluble  in  water  and  does 
not  alter  the  colour  of  litmus  paper.  Acids  decompose  it  into  oxide  of 
copper  and  peroxide  of  hydrogen. 

REFERENCES.  Prousfs  Experiments  on  Copper  and  its  compounds,  Ann, 
de  Chin,  xxv.  or  Repert.  of  Arts,  1st  sfr.  xiv.  114,  201,  Chenemx,  in.  Phil. 
Trans,  for  1806.  Thenard,  Truite  de  Chin,  ii.  379,  where  three  Oxides  are 
described — and  Berzelius,  iii.  128. 

COPPER  AND  CHLORINE. 

From  the  researches  of  Proust  and  Dr.  J.  Davy,  there  appears  to  be 
no  doubt  that  there  are  two  compounds  of  these  substances,  and  that 
they  are  proportional  to  the  oxides  of  copper. 

Subchloride  of  Copper. — Atom.  Num.  98-65 — Symb. 
Cl+2Cu. 

SYN.     Rosin  of  Copper— Boyle.      White  Muriate  of  Copper— Proust. 
PROPERTIES.     Colour  varying  with  the  mode  of  preparation,  being 


COPPER.  331 

white,  yellow,  or  dark  brown  ;  it  is  insoluble  in  water,  but  soluble  in 
muriatic  acid,  and  is  precipitated  unchanged  by  water  ;  is  fusible  at  a 
heat  just  below  redness,  and  bears  a  red  heat  in  close  vessels  without 
subliming. 

PREPARATION.  This  compound  may  be  conveniently  prepared  by 
heating  copper  filings  with  twice  their  weight  of  corrosive  sublimate  ; 
or  by  the  action  of  protornuriate  of  tin  on  the  muriate  of  copper;  and 
also  by  decomposing  the  muriate  by  heat. 

Chloride  of  Copper. — Atom.  Num.  67-05 — Symb.  Cl-j-Cu. 

A  pulverulent  substance  of  a  yellow  colour,  which  deliquesces  on 
exposure  to  the  air,  and  is  reconverted  by  water  into  the  muriate.  It  is 
formed  by  exposing  the  muriate  of  copper  to  a  temperature  not  exceed- 
ing 400 J  F.—Dr.  J.  Davy,  in  Phil.  Trans,  for  1812. 

COPPER  AND  SULPHUR. 

Disulphuret  of  Copper.— Atom.  Num.  79-2—  Symb.  S+2Cu. 

A  natural  production  well  known  to  mineralogists  under  the  name 
of  Copper  Glance ;  and  in  combination  with  sulphuret  of  iron,  it  is  a 
constituent  of  the  variegated  copper  ore.  It  is  formed  artificially,  by 
heating  copper  filings  with  a  third  of  their  weight  of  sulphur.  The 
combination  is  attended  with  such  free  disengagement  of  caloric,  that 
the  mass  becomes  vividly  luminous. 

Sulphuret  of  Copper. — Atom.  Num.  47*6 — Symb.  S+Cu. 

A  constituent  of  Copper  Pyrites,  in  which  it  is  combined  with  pro- 
tosulphuret  of  iron.  It  may  be  formed  artificially  by  the  action  of 
sulphuretted  hydrogen  on  a  per-salt  of  copper.  When  exposed  to  a 
red  heat  in  a  close  vessel,  it  loses  half  its  sulphur,  and  is  converted  in- 
to a  protosulphuret. 

It  is  from  this  compound  that  most  of  the  copper  of  commerce  is 
obtained.     The  small  quantity  of  arsenic,  and  the  sulphur   which  it 
contains,  are  separated  by  roasting  ;  and  the  copper  is  obtained  by  re 
peated   fusions,  in  some  of  which  an  addiiion  of  charcoal   is   made. 
See  R.  Phillips  on  Yellow  Copper  Ore,  Ann.  of  Phil.  xix.  296. 

COPPER  AND  PHOSPHORUS. 

Copper  unites  by  fusion  with  phosphorus.  The  phosphuret  is  white, 
brittle,  and  of  the  specific  gravity  7 '122.  It  consists  of  one  atom  phos- 
phorus-f-2  atoms  copper.  There  are  probably  several  distinct  phos- 
phurets  of  copper. 


COPPER  AND  THE  METALS. 

Many  of  the  alloys  of  copper  are  of  the  highest  importance  in  do- 
mestic economy  and  the  arts. 


g 
le 


332  COPPER. 

Copper  may  be  united  to  iron  by  fusion,  but  not  without  some  diffi- 
culty. It  is  an  alloy  of  a  gray  colour,  has  but  little  ductility  and  is 
much  less  fusible  than  copper.  According  to  Thenard  it  is  attracted 
by  the  magnet  even  when  the  iron  constitutes  only  1-10  of  the  alloy. 
[Ann,  de  Cfdm.  1.  131.]  And  from  some  observations  of  M.  Levavas- 
seur  it  appears  probable  that  the  variety  of  iron,  called  hot  short  iron, 
because  it  is  brittle  when  red  hot,  owes  its  peculiarity  to  the  presence 
of  copper.  —  See  Thomson's  Inorg.  Chem.  i.  598. 

Bronze,  is  an  alloy  of  11  parts  of  tin  to  100  of  copper.  It  is  of  a 
rayish-yellow  colour,  harder  and  more  fusible  than  copper;  slightly  mal- 
eable when  slowly  cooled,  and  very  much  so  when  heated  to  near 
redness  'and  then  plunged  into  cold  water.  In  consequence  of  the  fu- 
sibility of  this  alloy,  it  is  much  used  in  the  casting  of  statues.  Ac- 
cording to  Puyrnaurin,  the  finest  French  bronze  medals  consist  of  from 
7  to  11  of  tin  and  100  of  copper.  —  Thenard,  i.  629. 

Bell  Metal,  is  an  alloy  of  22  parts  of  tin  and  78  of  copper.  It  is 
solid,  fine  and  close  grained,  of  a  grayish-white  colour,  and  more  fusi- 
ble than  bronze.  The  Chinese  Tarn-Tain  or  Gong,  so  celebrated  for 
the  richness  of  its  tones,  contains,  acccording  to  the  analysis  of  The- 
nard, 80  parts  of  copper  and  20  of  tin.  Speculum  Metal,  from  which 
the  mirrors  of  telescopes  are  made,  contains  about  two  parts  of  copper 
and  one  of  tin.  The  whiteness  of  the  alloy  is  improved  by  the  addi- 
tion of  a  little  arsenic. 

Brass,  consists  of  copper,  alloyed  with  from  12  to  25  per  cent,  of 
zinc  ;  the  proportions  differing  somewhat  in  almost  every  place  in 
which  it  is  manufactured.  It  has  a  yellow  colour,  is  very  malleable 
and  ductile  when  cold,  but  fragile  at  an  elevated  temperature.  The 
preparation  consists  in  uniting  directly  the  proper  proportions  of  zinc 
and  copper,  in  the  ordinary  way,  or  in  heating  a  mixture  of  carbon, 
copper  and  calamine,  (carbonate  of  zinc,)  which  is  an  abundant  natu- 
ral product. 

The  compounds  known  under  the  names  of  Tombac,  Dutch  Gold. 
Prince  Rupert's  Metal,  or  Pinchbeck,  are  alloys,  containing  more  copper 
than  exists  in  brass,  and  they  are  consequently  made  by  fusing  various 
proportions  of  copper  with  brass. 

The  art  of  tinning  copper  consists  in  applying  to  this  metal  a  very 
thin  covering  of  tin,  in  order  to  protect  its  surface  from  oxidation. 
The  copper  is  first  sprinkled  over  with  some  muriate  of  ammonia  ;  it 
is  then  heated  and  rubbed  with  this  salt.  When  the  copper  is  perfect- 
ly clean,  small  fragments  of  tin  are  placed  upon  it,  and  it  is  then  heat- 
ed sufficiently  for  melting  the  tin  ;  this,  when  liquified,  is  rubbed  over 
the  whole  sheet  of  copper,  and  if  the  process  is  dexterously  perform- 
ed, adheres  uniformly  to  its  surface.* 


*  According  to  Mr.  Donoran  the  coat  of  tinning1  which  is  given  to  the  inside 
of  copper  vessels  is  in  fact  a  mixture  of  had  and  tin  ;  and  the  use  of  it  is  to 
prevent  the  copper  from  coming  in  contact  with  the  food  prepared  in  such  a 
vessel,  which  might  otherwise  be  impregnated  with  that  poisonous  metal. — 
Although  lead  itself  is  a  poisonous  metal,  it  is  singular  that  the  presence  of 
tin  renders  it  innoxious  ;  the  reason  of  which  is  that  tin  prevents  the  lead  from 
dissolving.  Pewter  is  composed  of  lead  in  tin;  and  on  account  of  the  pres- 
ence of  the  latter,  the  former  is  rendered  safe. — Donoraifs  Chemistry,  249. 


COPPER.  333 

REFERENCES.  Bishop  Watson's  Chemical  Essays,  ir.  Aikin's  Chem» 
Diet,  article,  Brass,  #e.  Thenard,  Traite  de  Chim.  i.  628.  The  art.  Brass, 
by  Mr.  C.  Sylvester  j  and  the  art.  on  Bronzing,  by  J.  G.  Daly  ell,  in  the  Supp* 
totiie  Ediri.  Encyclopoedia.  DaltoiSs  New  Syst.  ii. 

SALTS  OF  COPPER. 

Muriates  of  Copper. — Corresponding  with  the  two  chlorides  of  cop- 
per we  have  also  a  Submuriate  and  a  Muriate.  The  former  is  obtained 
by  digesting  metallic  copper  in  muriatic  acid,  with  the  oxide — The 
latter  by  dissolving  oxide  of  copper  in  muriatic  acid. 

Nitrate  of  Copper.— Atom.  Nam.  156'6— -  Symb.   (5O+N.) 
+(0+Cu.)-j-7Aq. 

PROPERTIES.  This  salt  crystallizes,  though  with  some  difficulty,  in 
prisms,  which  are  of  a  deep  blue  colour,  and  deliquesce  on  exposure  to 
the  air  ;  by  exposing  them  to  heat,  a  green  insoluble  Sub-nitrate  is  form- 
ed, which  contains,  exclusive  of  water,  one  atom  of  acid  and  two  atoms 
of  the  oxide. 

When  crystals  of  nitrate  of  copper  are  coarsely  powdered,  sprink- 
led with  a  little  water  and  quickly  rolled  up  in  a  sheet  of  tin  foil,  there 
is  great  heat  produced,  nitrous  gas  is  rapidly  evolved,  and  the  metal 
often  takes  fire.  These  crystals  also  detonate  when  mixed  with  phos- 
phorus and  struck  with  a  hammer. 

This  salt  is  prepared  by  the  action  of  nitric  acid  on  copper. 

Jmmoniuret  of  Copper. — Copper  and  its  oxides  are  soluble  in  ammo- 
nia. The  watery  solution  of  ammonia,  at  its  boiling  temperature, 
acts  rapidly  on  copper.  Dry  ammoniaca!  gas  appears  also  to  combine 
with  heated  copper.  [Brandes  Journal,  29,  158.]  If  ammonia  be  ad- 
ded in  excess  to  nitrate  of  copper,  the  precipitate  which  is  first  formed 
is  re-dissolved.  On  this  property  depends  the  method  of  separating 
oxide  of  copper  from  other  metallic  oxides  ;  from  those  of  iron,  for 
instance,  which  are  not  soluble  by  ammonia. — Henry,  ii.  112. 

Oxide  of  copper  digested  in  ammonia,  forms  a  bright  blue  liquid  ; 
from  which  by  careful  evaporation,  fine  blue  crystals  may  be  obtained, 
called  Ammoniurct  of  Copper.  Suboxide  of  copper  also  dissolves  in 
ammonia,  and  yields  a  colourless  solution,  which  becomes  blue  by  ex- 
posure to  the  air,  in  consequence  of  the  absorption  of  oxygen. 

Plates  of  copper  digested  in  a  solution  of  muriate  of  ammonia,  are 
soon  incrusted  with  a  green  powder,  which  has  been  used  in  the  arts 
under  the  name  of  Brunswick  Green. 

Sulphate  of  Copper.— Atom.  Num.   124-6— %»i&.  (3O+S.) 
+(0+Cu.)+5Aq. 

SYN.     Blue  Vitriol — Roman  Vitriol. 

This  salt  is  crystalline,  of  a  fine  blue  colour,  and  soluble  in  four 
parts  of  water  at  603  F. ;  it  slightly  effloresces  on  exposure  to  the  air, 
and  undergoes  by  a  gentle  heat  the  aqueous  fusion.  The  solution  of 
this  salt  is  decomposed  by  pure  and  carbonated  alkalies.  The  former, 
however,  re-dissolve  the  precipitate.  Thus  on  adding  pure  liquid  am- 
monia to  a  solution  of  sulphate  of  copper,  a  precipitate  appears,  which 

V 


334  COPPER. 

on  a  farther  addition  of  the  alkali  is  re-dissolved,  and  affords  a  beau- 
tiful bright  blue  solution. 

PREPARATION.  This  salt  may  be  prepared  for  chemical  purposes  by 
dissolving  black  oxide  of  copper  in  dilute  sulphuric  acid  ;  but  it  is  pro- 
cured for  sale  by  roasting  the  native  sulphuret.  It  is  used  in  medicine 
as  an  escharotic  ;  in  the  arts,  for  obtaining  Scheele's  green,  &c. 

This  salt,  as  well  as  most  of  the  soluble  salts  of  copper,  is  poisonous 
when  taken  internally.  The  remedy  proposed  by  Orfila  in  such  cases 
is  albumen,  with  which  oxide  of  copper  forms  an  inert  compound.  See 
Christison  on  Poisons,  353. 

There  appears  to  be  no  sulphate  of  the  suboxide  of  copper. 

Disulphate  of  Copper,  is  formed  by  adding  solution  of  potassa  to  the 
above  sulphate.  It  is  a  pale  bluish  green  powder,  and  is  composed 
of  one  atom  of  acid-f-tvvo  atoms  of  the  oxide. 

Phosphate  of  Copper. — This  has  not  yet  been  formed  artificially,  but 
has  been  found  native  in  a  white  quartz  rock.  It  is  of  an  emerald- 
green  colour,  and  is  not  crystallized. — Henry,  ii  115.  Lunn's  Analysis 
of  native  Phosphate  of  Copper,  Ann.  of  Phil.  xix.  179. 

Biphospkate  of  Copper. — A  bluish -green  salt,  formed  by  mingling  to- 
gether phosphate  of  soda  and  sulphate  of  copper. 

Carbonate  of  Copper. — According  to  Mr.  Phillips,  three  native  car- 
bonates of  copper  are  at  present  known, — the  green,  the  blue,  and  the 
anhydrous.  The  green  is  the  beautiful  mineral  known  by  the  name  of 
Malachite,  and  consists  of  one  atom  of  carbonic  acid,  two  atoms  oxide 
of  copper,  and  one  of  water.  A  similar  compound  may  be  made  from 
the  persulphate  by  double  decomposition,  or  by  exposing  metallic  cop- 
per to  air  and  moisture. 

The  blue  pigment  called  Vcrditer,  said  to  be  prepared  by  decompos- 
ing nitrate  of  copper  by  chalk,  is  an  impure  carbonate.  On  the  Car- 
bonates of  Copper  and  the  preparation  of  Verditer,  sec,  the  valuable  Essay 
of  Mr.  Phillips,  in  Brandes  Jour.  iv.  273. 

Ferrocyanate  of  Copper  is  a  brown  compound,  obtained  by  adding 
ferrocyanate  of  potassa  to  a  dilute  solution  of  sulphate  or  nitrate  of 
copper.  Mr.  Hatchett  has  recommended  this  substance  as  a  brown 
pigment. — Repcrt.  of  Arts,  2d  ser.  ii.  180. 

Chromate  of  Copper. — This  salt  is  prepared  by  precipitating  sulphate 
of  copper  by  chromate  of  potash.  It  is  of  a  reddish  brown  colour,  is 
soluble  in  dilute  solution  of  ammonia,  producing  a  clear  solution  of  a 
beautiful  and  deep  green  colour.  When  the  solution  is  evaporated,  the 
reddish  chromate  of  copper  appears  as  the  ammonia  flies  off.  The 
readiest  way  of  preparing  this  permanent  and  beautiful  colour,  is  to 
add  solution  of  chromate  of  potash  to  ammoniacal  sulphate  of  copper. 

The  Acetates  of  Copper  will  be  noticed  under  Acetic  acid. 

TESTS  OF  THE  SALTS  OF  COPPER.  The  cupreous  salts  are  nearly  all 
soluble  in  water,  and  of  a  blue  or  green  colour.  Ammonia  produces 
a  compound  of  a  very  deep  blue,  when  added  in  excess  to  these  solu- 
tions ;  hydrosulphuret  of  ammonia  forms  a  black  precipitate  ;  and  a, 
plate  of  iron  plunged  into  a  liquid  salt  of  copper,  precipitates  metallic 
copper.  Ferrocyanate  of  potassa  is  also  an  excellent  test  of  the  pres- 
ence of  copper  ;  it  produces  a  brown  cloud  in  solutions  containing  the 
oxide.  All  the  salts  of  copper  communicate  a  green  tint  to  inflamma- 
ble matter  in  a  state  of  combustion  when  moistened. 


LEAD.  335 

SECTION  XXXIV. 

LEAD. 
Atom.  JYwwi.  103-5.—  fifywzA.  Pb*—  Sj).  gr.  11-352. 


Known  from  the  most  remote  antiquity,  and  called  Saturn  by  the 
Alchemists. 

PROPERTIES.  This  metal  is  of  a  bluish-white  colour,  and  when  re- 
cently cut  or  melted,  exhibits  considerable  lustre,  which  soon,  how- 
ever, tarnishes;  its  malleability  is  sufficient  to  allow  of  its  being  beat- 
en into  very  thin  leaves  ;  and  it  may  be  drawn  into  wire,  which  has 
less  tenacity,  however,  than  that  of  most  other  metals  ;  it  melts,  ac- 
cording to  Morveau,  at  590°  F.  but  according  to  Mr.  Crichton,  of 
Glasgow,  at  612D  ;  exposed  to  a  red  heat,  with  free  access  of  air,  it 
smokes  and  sublimes,  and  gives  off  a  gray  oxide,  which  collects  on 
surrounding  bodies  ;  it  is  slowly  oxidized  also,  by  exposure  to  the  at- 
mosphere at  common  temperatures,  and  more  rapidly  when  exposed 
alternately  to  the  action  oif  air  and  water.  Many  spring-  waters,  how- 
ever, owing  to  the  salts  which  they  contain,  do  not  corrode  lead.  —  On 
this  subject,  see  Christison  on  Poisons,  391. 

NATIVE  STATE  AND  PREPARATION.  —  Native  lead  is  an  exceedingly  rare 
production,  but  in  combination,  especially  with  sulphur,  it  occurs  in 
large  quantity.  From  the  native  sulphuret,  the  Galena  of  mineralo- 
gists, all  the  metallic  lead  of  commerce  is  extracted. 

This  lead  generally  contains  copper  and  iron,  and  sometimes  traces 
of  silver.  To  obtain  it  in  a  state  of  perfect  purity,  it  should  be  dis- 
solved in  nitric  acid,  and  the  solution  evaporated  and  crystallized  sev- 
eral times.  The  resulting  nitrate  reduced  to  powder,  is  to  be  strongly 
heated  in  a  Hessian  crucible  to  drive  off  the  nitric  acid,  and  then  melt- 
ed in  contact  with  a  small  quantity  of  charcoal.  —  tierzelius,  Trait,  de 
Chiin.  iii.  176. 

LEAD  AND  OXYGEN. 

There  appear  to  be  three  oxides  of  lead.  These  have  been  examin- 
ed with  great  care  by  Berzelius. 

Protoxide  of  Lead.  —  Atom.  Num.  —  111-5  —  Symb.  O+Pb. 

PROPERTIES.  Yellow,  tasteless,  insoluble  in  water,  but  soluble  in 
potassa  and  in  acids  ;  when  heated  it  forms,  on  cooling-,  a  yellow  semi- 
transparent  glass,  called  Litharge,  which  is,  to  a  considerable  degree, 
volatile  at  a  red  heat,  and  has  been  obtained  in  regular  crystals.  [Phil. 
Mag.  and  Ann.  i.  3J2.]  Another  form  of  the  yellow  oxide  is,  that 
which  is  known  in  commerce  by  the  name  of  Massicot. 

PREPARATION.  The  yellow  oxide  may  be  obtained  by  decomposing 
nitrate  of  lead  with  carbonate  of  soda,  and  igniting  the  precipitate,  or 
by  heating  the  nitrate  to  redness  in  a  close  vessel.  Massicot  is  pre- 
pared by  collecting  the  gray  film  which  forms  on  the  surface  of  melted 
lead,  and  exposing  it  to  heat  and  air,  until  it  acquires  a  uniform  yellow 
colour. 


*  From  the  latin  word  Plumbum. 


336  LEAD. 

Sesquioxide  of  Lead. — Atom.  Num.  1155— Symb.  l|O-j-Pb. 

This  oxide,  which,  in  an  impure  form,  is  the  Minium  or  Red  Lead 
of  commerce,  does  not  unite  with  acids  ;  when  heated  to  redness  it 
<rives  off  pure  oxygen  gas,  and  is  reconverted  into  the  protoxide  ;  when 
digested  in  nitric  acid,  it  is  resolved  into  the  protoxide  and  peroxide  of 
lead,  the  former  of  which  unites  with  the  acid,  while  the  latter  re- 
mains as  an  insoluble  powder. 

This  compound  is  formed  by  heating  litharge  in  open  vessels,  while 
a  current  of  air  is  made  to  play  upon  its  surface.  The  common  red 
lead  generally  contains  a  proportion  of  protoxide  and  sulphate  of  lead, 
and  other  impurities. 

Peroxide  of  Lead.— Atom.  Num.  U9'5—Symb.  2O+Pb. 

This  oxide  is  of  a  puce  colour,  does  not  unite  with  acids,  and  by  a 
red  heat  is  resolved  into  the  protoxide  and  oxygen  gas. 

It  may  be  obtained  by  the  action  of  nitric  acid  on  minium  ;  but  the 
most  convenient  method  of  preparing  it,  is  by  transmitting  a  current 
of  chlorine  gas  through  a  solution  ot  the  acetate  of  lead.  In  this  pro- 
cess, water  is  decomposed  ;  its  hydrogen  uniting  with  chlorine,  and  its 
oxygen  with  the  protoxide  of  lead,  give  rise  to  muriatic  acid,  and  the 
peroxide  of  lead. 

REFERENCES.  Berzelius  on  the  Oxides  of  Lead,  Ann.  of  Phil  xv.  94. — 
Longchanip,  Ann.  de  C'lim.  et  de  Pliys.  xxxiv.  105,  who  denies  that  Minium 
is  a  peculiar  Oxide  of  Lead.  Thomson's  First  Pritt.  i.  396.  On  the  manu- 
facture of  Red  Lead,  see  Aikiii's  C/tem.  Diet,  and  Watson's  Chein.  Essays. 

LEAD    AND    CHLORINE. 

Chloride  of  Lead.— Atom.  Num.  138-95— Symb.  Cl+Pb. 

PROPERTIES.  This  compound  has  a  sweet  taste,  and  is  soluble  in  22 
parts  of  water  at  6lP  F.,  and  also  in  dilute  nitric  acid  ;  when  dry  it  is 
fusible  at  a  heat  below  redness,  into  a  semi-transparent  substance  of 
the  consistence  of  horn,  from  whence  it  has  been  called  Horn  Lead,  or 
Plumbum  Lorneum;  by  an  intense  heat  it  is  volatilized. 

It  is  slowly  formed  by  the  action  of  chlorine  gas  on  thin  plates  of 
lead,  and  may  be  obtained  more  easily  by  adding  muriatic  acid  or  a 
solution  of  sea-salt,  to  the  acetate  or  nitrate  of  lead  dissolved  in  wa- 
ter. 

Mineral  or  Patent  Ydlow. — The  pigment  known  under  this  name  is 
a  compound  of  the  chloride  and  protoxide  of  lead.  It  is  prepared  for 
the  purposes  of  the  arts  by  the  action  of  moistened  sea  salt  on  lith- 
arge, by  which  means  a  portion  of  the  protoxide  is  converted  into  chlo- 
ride of  lead,  arid  then  fusing  the  mixture.  Soda  is  set  free  during 
this  process,  and  is  converted  into  a  carbonate  by  absorbing  carbonic 
acid  from  the  atmosphere. 


LEAD.  337 

LEAD    AND    IODINE. 

Iodide  of  Lead.-- Atom.  Num.  229-5— Symb.  I-j-Pb. 

This  compound  is  easily  formed  by  mixing  a  solution  of  hydriodic 
acid  or  hydriodate  of  potassa  with  the  acetate  or  nitrate  of  lead  dis- 
solved in  water.  It  is  of  a  rich  yellow  colour  ;  is  dissolved  by  boiling 
water,  forming  a  colourless  solution,  and  is  deposited,  on  cooling,  in 
yellow  crystalline  scales  of  a  brilliant  lustre. 

LEAD    AND    SULPHUR. 

Sulphuret  of  Lead.— Atom.  Num.  119  5—  Symb.  S-fPb. 

This  is  an  abundant  natural  product,  known  by  the  name  of  Galena, 
from  which  the  lead  of  commerce  is  obtained  by  roasting  the  ore  to 
drive  off  the  sulphur.  It  occurs  massive  and  crystallized,  the  primi- 
tive form  being  the  cube.  It  often  contains  traces  of  silver  in  such 
quantity  as  to  be  worth  the  trouble  of  separation.  It  occurs  very 
abundantly  in  the  western  parts  of  the  United  States.  It  may  be  made 
artificially  either  by  heating  together  lead  and  sulphur,  or  by  the  ac- 
tion of  sulphuretted  hydrogen  on  a  salt  of  lead. 

There  appear  to  be  two  other  sulphurets  of  lead,  which  Dr.  Thom- 
son names  Disulphuret  and  Risulphuret  of  Lead. — Inorg.  Chem.  i.  566. 

Lead  may  be  also  made  to  combine  with  phosphorus  and  carbon. 

REFERENCES.  Dcscostils  on  the  Sulphuret  of  Lead,  copied  from  Memoirs 
D'Arcueil,  in  Repert.  of  Arts,  %d  ser.  xvi.  280.  BerthieSs  Memoir  on  the 
decomposition  of  Sulphuret  of  Lead  by  Carbonate  of  Soda,  Ann.  de  Chim. 
et  de  Phys.  xxxiii.  T54.  On,  the  reduction  of  Lead  from  the  sulphuret,  fyc., 
see  AikirCs  Chem.  Diet,  and  Dr.  Cooper,  in  Emporium  of  Arts,  v.  177. 

LEAD    AND    THE    METALS. 

The  alloys  of  lead  are  quite  numerous  ;  but  those  which  it  forms 
with  tin  are  the  most  important.  The  compound  of  one  part  of  tin 
and  two  of  lead  is  known  by  the  name  of  Plumber's  solder,  from  the 
uses  to  which  it  is  applied.  If  we  employ  3  parts  of  lead,  the  com- 
pound is  still  more  fusible.  Common  Pewter  consists  of  80  parts  of 
tin  and  20  of  lead  ;  and  what  is  termed  Pot  metal,  consists  of  copper 
with  about  a  fourth  of  its  weight  of  lead. 

Lead  when  added  only  in  small  quantities,  impairs  the  ductility  of 
silver  and  gold. 


338  LEAD. 

SALTS    OF    LEAD. 

The  salts  of  lead  all  contain  the  protoxide  as  the  basis. 

Nitrate  of  Lead.— Atom.  Num.  165-5—  Symb.  (5O+N)+ 
(0+Pb.) 

This  salt  occurs  in  large  white  opake  octahedral  crystals,  which  are 
anhydrous,  and  have  an  acid  reaction,  though  neutral  in  their  compo- 
sition. It  is  prepared  by  digesting  litharge  in  dilute  nitric  acid. 

A  subnitrate  or  dinilrate  of  lead,  composed  of  one  proportion  of  acid 
to  two  proportions  of  the  protoxide,  was  formed  by  Berzelius  by  add- 
ing to  a  solution  of  the  neutral  nitrate,  a  quantity  of  pure  ammonia, 
insufficient  for  separating  the  whole  of  the  acid. 

Sulphate  of  Lead.— Atom.  Num.  151-5— Symb.  (3O+S)+ 
(0+Pb.) 

This  salt  occurs  native  in  regular  crystals,  though  from  its  insolubi* 
lity  it  cannot  be  crystallized  artificially.  The  primary  form  of  the 
crystals  is  a  right  rhombic  prisrn.  It  is  anhydrous,  though  there  is 
usually  a  trace  of  water  mechanically  lodged  between  the  plates  of 
the  crystals.  Its  insolubility  both  in  water  and  in  nitric  acid,  renders 
its  formation  of  use  as  a  step  in  mineral  analyses.  Hence  also  it  is 
not  poisonous,  and  therefore  any  soluble  sulphate  renders  the  active 
salts  of  lead  inert. 

Sulphuric  acid  can  only  be  made  to  act  upon  lead  when  concentrat* 
ed,  and  at  a  boiling  temperature,  and  hence  lead  is  employed  in  con- 
structing chambers  for  the  manufacture  of  this  acid.  Sulphate  of  lead 
may,  however,  be  artificially  prepared  by  adding  sulphuric  acid,  or  still 
better,  sulphate  of  soda,  to  any  of  the  salts  of  lead. 

DEFERENCES.  Rerthier  on  ttie  uses  to  whi<:h  Sulphate  of  Lead  may  be  ap. 
plied  in  the  arts,  Ann.  de  Chim.  or  Repert.  of  Arts,  2d  *er.  xlii.  110,  184. 

Phosphate  of  Lead.— Atom.  JVW.  147-2—  Symb.  (2JO+P) 
+  (0+Pb.) 

This  salt  is  of  a  yellowish  white  colour,  insoluble  in  water,  soluble 
in  alkaline  solutions  and  in  nitric  acid  ;  is  decomposed  by  sulphuric 
and  hot  muriatic  acid  ;  fuses  before  the  blow-pipe,  and  crystallizes  on 
cooling. 

Phosphate  of  lead  exists  native,  and  is  often  crystallized  in  six-sided 
prisms.  It  is  formed  artificially  by  mixing  solutions  of  nitrate  of  lead 
and  phosphate  of  soda,  or  phosphoric  acid. 

According  to  Thomson  there  is  also  a  Diphosphate  of  Lead,  consist- 
ing of  on*  proportion  of  phosphoric  acid  and  two  proportions  of  pro- 
toxide of  lead.—  First  Prin.  ii.  370. 


LEAD.  339 

Carbonate  of  Lead.— Atom.  JVwnt,  133-5—  Symb.  (2O-f  C)  + 
(0+Pb.) 

This  salt,  which  is  the  White  Lead  or  Ceruse  of  painters,  occurs  na- 
tive, but  may  be  obtained  by  double  decomposition.  It  is  prepared  for 
the  purposes  of  commerce  by  exposing  coils  of  thin  sheet  lead  to  the 
vapour  of  vinegar,  when  by  the  action  of  the  acid  fumes,  the  lead  is 
both  oxidized  and  converted  into  a  carbonate. 

This  substance  in  commerce  is  often  adulterated  with  chalk,  sul- 
phate of  lead  and  sulphate  of  barytes. 

REFERENCES.  For  the  process  of  making  White  Lead,  see  Aikut'*  Chem. 
Diet.  art.  Lead.  For  notices  of  other  Salts  of  Lead,  see  Thomson's  First 
Prin.  ii.  367.  Chevreul  on  the  Nitrates  and  Nitrites  of  Lead,  Ann.  of  Phil. 
\.  301.  Berzelius1  Analyses  of  the  Salts  of,  Ann.  of  Phil.  vii.  40.  On  the 
poisonous  properties  of  these  Salts,  consult  Christison  on  Poisons.* 

TESTS  OF  THE  SALTS  OF  LEAD.  The  soluble  salts  of  lead  have  a 
sweetish  austere  taste,  and  are  characterized  by  the  white  precipitate 
produced  by  ferroeyanate  of  potassa,  the  deep  brown  by  hydrosulphur- 
et  of  ammonia,  and  the  yellow  by  hydriodate  of  potassa. 

The  salts  insoluble  in  water  are  dissolved  by  soda,  potassa,  and  by 
nitric  acid,  when  the  metal  is  rendered  manifest  by  sulphuretted  hy- 
drogen, and  other  tests.  Heated  by  the  blow-pipe  upon  charcoal,  they 
afford  a  button  of  metal. 


*  Dr.  Turner,  upon  the  authority  of  Dr.  A.  T.  Thomson,  states  a  curious 
fact  wsth  regard  to  the  poisonous  property  of  the  salts  of  lead  ;  which  is,  that 
of  all  the  ordinary  preparations  of  lead,  the  carbonate  is  by  far  the  most  viru- 
lent poison.  Any  salt  of  lead  which  is  easily  convertible  into  the  carbonate, 
as  for  instance,  tho  subacetate,  is  also  poisonous;  but  Dr.  Thomson  has  given 
Jarge  doses  of  the  nitiate  and  muriate  of  lead  to  rabbits  without  producing 
perceptible  inconvenience.  He  finds  that  acetate  of  lead,  mixed  with  vinegar 
to  prevent  the  formation  of  any  carbonate,  may  be  freely  and  safely  administer- 
ed in  medical  practice. — Turner's  Chem.  4th  ed.  589, 


340  MERCURY. 


CLASS  VI. 


METALS,  THE  OXIDES  OP  WHICH  ARE  DECOMPOSED  BY  A  RED 
HEAT. 


SECTION   XXXV. 

MERCURY. 
Atom.  JYMOT.  2W.—Symb.  Fg*.— Sp.  gr.  13568. 

This  metal  was  known  to  the  ancients.  It  received  the  name  of 
Quicksilver  from  the  alchemists.  It  occurs  native,  or  in  combination 
with  sulphur,  forming  Cinnfibar,  from  which  the  metal  may  be  separat- 
ed by  distillation  with  quicklime  or  iron  filings. 

PROPERTIES.  Mercury  is  distinguished  from  all  other  metals  by  be- 
ing fluid  at  the  ordinary  temperature  ;  it  lias  a  tin-white  colour,  and 
strong  metallic  lustre  ;  becomes  solid  at  the  temperature  of  39°  or 
40°  below  zero,  and  in  congealing,  evinces  a  strong  tendency  to  crys- 
tallize in  octahedrons  ;  it  contracts  greatly  at  the  moment  of  congela- 
tion, for  while  its  density  at  47 J  F.  is  13-545,  the  specific  gravity  of 
frozen  mercury  is  15-612  ;  when  solid  it  is  malleable,  and  may  be  cut 
with  a  knife  ;  at  662°  F.  according  to  Petit  and  Dulong,  it  enters  into 
ebullition,  and  condenses  again  on  cool  surfaces  into  metallic  glo- 
bules;  it  is  not  changed  by  the  action  of  air  at  common  tempera- 
tures ;  it  is  acted  on  by  nitric  and  hot  sulphuric  acids ;  and  vapour- 
izes  in  vacuo  at  common  temperatures. — Faraday,  Brande's  Jour.  x. 
3^4. 

Malleability  of  solid  Mercury. — During  Capt.  Parry's  first  voyage  to 
the  Arctic  Regions,  on  February  the  14th  and  15th,  (1820)  the  ther- 
mometer continued  for  15  hours  at  from  —  54°  to  —  55°  F.  Some 
mercury  was  frozen  during  the  continuance  of  this  cold  weather,  and 
beaten  out  on  an  anvil,  previously  reduced  to  the  temperature  of  the 
atmosphere  ;  it  did  not  appear  to  be  very  malleable  in  this  state,  usual- 
ly breaking  after  two  or  three  blows  from  the  hammer.  This  experi- 
ment was  also  tried  some  years  since  at  Hudsonrs  Bay.  The  mercury 
when  frozen  was  reduced  to  sheets  as  thin  as  paper.  And  on  plunging 
a  mass  of  this  frozen  metal  into  a  glass  of  warm  water,  the  mercury 
became  fluid  and  the  water  was  immediately  frozen.  By  the  rapidity 
of  the  action  the  glass  was  shivered  into  a  thousand  pieces. 

ADULTERATION.  Mercury  is  sometimes  adulterated  with  the  alloy  of 
lead  and  bismuth,  a  fraud  which  is  easily  detected  by  the  want  of  its 

*  From  the  latin  word  Hydrargyrum. 


MERCURY.  341 

due  fluidity,  and  by  its  not  being  perfectly  volatile,  but  leaving  a  resi- 
duum  when  boiled  in  a  platinum  or  iron  spoon.     The  best  method  of 
purifying  mercury  is  to  re-distil  it  in  an  iron  retort. — See  Ure's  Chemi 
cal  Dictionary. 

MERCURY    AND    OXYGEN. 

Mercury  is  susceptible  of  two  stages  of  oxidation,  and  both  its  ox- 
ides are  capable  of  forming  salts  with  acids. 

Protoxide  of  Mercury. — Atom.  Num.  208 — Symb.  O+Hg. 

SVN.     Hydrargyri  Oxidum  Cinereum. — U.  S.  Phar. 

A  black,  insoluble,  insipid  powder  ;  best  prepared  by  the  process 
recommended  by  Donovan.  This  consists  in  mixing  calomel  briskly 
in  a  mortar  with  pure  potassa  in  excess,  so  as  to  effect  its  decomposi- 
tion as  rapidly  as  possible.  The  protoxide  is  then  to  be  washed  with 
cold  water,  and  dried  spontaneously  in  a  dark  place.  These  precau- 
tions are  rendered  necessary  by  the  tendency  of  the  protoxide  to  re- 
solve itself  into  the  peroxide  and  metallic  mercury,  a  change  which  is 
easily  effected  by  heat,  by  the  direct  solar  rays,  and  even  by  day-light. 
It  is  on  this  account  very  difficult  to  procure  the  protoxide  of  mercury 
in  a  state  of  absolute  purity. — Ann.  of  Phil.  xiv.  241,  321. 

When  mercury  is  agitated  for  a  long  time  in  contact  with  air  it  be- 
comes converted  into  a  black  powder — to  which  Boerhaave  gave  the 
name  of  Ethiops  per  se.  This  was  formerly  supposed  to  be  the  pro- 
toxide, but,  as  pure  mercury  has  a  feeble  attraction  for  oxygen,  it  is, 
most  probably,  metallic  mercury  in  a  state  of  minute  division,  as  is 
maintained  by  Berzelius.  [Traite  de  Chim.  iii.  107.]  The  same  may 
be  said  of  all  the  medicinal  preparations  formed  by  triturating  metallic 
mercury  with  various  viscous  bodies,  as  oil,  fat,  gum,  &c. 

Peroxide  of  Mercury. — Atom.  Num.  216 — Symb.  2O+Hg. 

SYN.     Hydrargyri  Oxidum  Rubrum. — Lond.  Phar. 

PROPERTIES.  This  oxide  is  of  a  red  colour,  and  sparingly  soluble 
in  water,  forming  a  solution  which  has  an  acrid  metallic  taste,  and 
communicates  a  green  colour  to  the  blue  infusion  of  violets  ;  when 
heated  to  redness  it  is  converted  into  metallic  mercury  and  oxygen — 
and  the  same  effect  is  said  to  be  produced  by  long  exposure  to  light. 

PREPARATION.  Peroxide  of  mercury  may  be  formed  either  by  the 
combined  agency  of  heat  and  air,  or  by  dissolving  metallic  mercury  in 
nitric  acid,  and  exposing  the  nitrate  so  formed  to  a  temperature  just 
sufficient  for  expelling  the  whole  of  the  nitric  acid.  It  is  commonly 
known  by  the  name  of  Red  Precipitate. 

REFERENCES.  Donovan  on  the  Oxides  and  Salts  of  Mercury ,  Ann.  of 
Phil.  xiv.  241.  Sefstrom  and  Thomson,  samvwor/c,  xviii.  126.  Guibourt, 
Ann.  de  Chim.  et  de  Phys.  i.  422,  who  maintains  that  the  Protoxide  exists 
pure  ojily  in  combination  with  Acids.  On  the  methods  of  making  various 
Mercurial  Preparations,  see  the  controversy  between  Dr.  Hope  and  Mr.  Phii" 
lips,  in  Ann.  of  Phil.  xvii.  and  xviii.  Berzelius^  Traite  de  Chim.  iii.  10o* 
Carpenter  on  the  division  of  Mercury  by  trituration,  Sill.  Jour.  xii.  173. 


342  MERCURY. 


MERCURY    AND    CHLORINE. 

Protochloride  of  Mercury. — Atom.  Num.  23545 — Symb. 
Cl+Hg. 

SYN.     Calomel.  —Mild  Muriate  of  Mercury,  Sfc. 

PROPERTIES.  This  compound  when  obtained  by  sublimation,  oc- 
curs in  semi-transparent  crystalline  cakes  ;  but,  as  formed  by  precipi- 
tation, is  a  white  powder,  having  a  density  of  7 "2  ;  it  is  distinguished 
from  the  bichloride  by  not  being  poisonous,  by  having  no  taste,  and 
being  insoluble  in  water  ;  it  is  but  little  affected  by  acids,  but  pure  al- 
kalies decompose  it,  separating  the  black  protoxide  of  mercury  ;  when 
mixed  with  lime-water  it  forms  the  substance  called  in  medicine  Black 
Wash. 

NATIVE  STATE  AND  PREPARATION.  This  compound  is  a  rare  native 
production,  called  Horn  Quicksilver,  which  occurs  crystallized  in  quad- 
rangular prisms,  terminated  by  pyramids.  It  is  always  generated 
when  chlorine  comes  in  contact  with  mercury  at  common  tempera- 
tures. It  may  be  made  by  precipitation,  by  mixing  muriatic  acid  or 
any  soluble  muriate  with  a  solution  of  the  protonitrate  of  mercury. 
It  is  more  commonly  prepared  by  sublimation.  This  is  conveniently 
done  by  mixing  272  parts,  or  one  proportion,  of  the  bichloride  with 
200  parts,  or  one  proportion,  of  mercury,  until  the  metallic  globules 
entirely  disappear,  and  then  subliming  When  first  prepared  it  is  al- 
ways mixed  with  some  corrosive  sublimate,  and  therefore  should  be 
reduced  to  powder  and  well  washed  before  being  employed  for  chem- 
ical and  medical  purposes. 

REFERENCES.  For  details  of  the  processes  of  Scheele,  Chenevix  and 
others  i  see  Aikiifs  (2  he  in.  Diet,  and  tVefoter't  Brande.  Gray^s  Operative 
Chemist  contains  a  description  of  Howard's  plan  for  reducing  Calomel  to  a 
Jine  powder.  Whatton,  on  the  origin  of  the  name  of  Calomel,  Ann.  of  Phil. 
xviii.  427. 

Bichloride   of  Mercury. — Atom.  Awm.   270-9 — Symb. 
2Cl+Iig. 

SYN.  Corrosive  Sublimate. — Corrosive  Muriate  of  Mercury. — Per- 
chloride  of  M  rcury. 

PROPERTIES.  A  white  serni-transparent  mass,  sometimes  perfectly 
crystallized — [^nn.  of  Phil.  xxii.  285  ;]  it  has  an  acrid,  burning  taste, 
leaves  a  metallic  flavour  on  the  tongue,  and  in  solution  reddens  lit- 
mus ;  its  specific  gravity  is  5-2  ;  it  sublimes  at  a  red  heat  without 
change  ;  requires  twenty  times  its  weight  of  cold,  and  only  twice  its 
weight  of  boiling  water  for  its  solution,  and  is  deposited  from  the  lat- 
ter as  it  cools  in  the  form  of  prismatic  crystals  ;  is  soluble  also  in* ether 
and  in  strong  alcohol  ;  and  from  its  watery  solution  alkalies  throw 
down  the  red  peroxide,  that  produced  by  lime-water,  being  called  in 
medicine  Yellow  Wash. 

It  possesses  acid  properties. — It  has  been  shown  by  Bonsdorf  that 
corrosive  sublimate  possesses  the  characters  of  an  acid  arid  that  it  is 


MERCURY.  343 

capable  of  combining  with  other  chlorides  and  with  muriates.  A  class 
of  compounds  is  thus  formed  to  which  he  has  given  the  name  of 
Chloro-hydrar gyrates.  Dr.  Thomson  desciibes  nineteen  of  these  com- 
pounds of  which  the  White  Precipitated  Mercury  is  one.  —  See  Thomson  s 
Jnorg.  Chem. 

PREPARATION.  This  chloride  is  formed  by  heating  metallic  mercu- 
ry in  chlorine  gas.  But  it  is  prepared  for  medicinal  purposes  by  sub- 
liming a  mixture  of  the  bipersulphate  of  mercury  with  the  chloride  of 
sodium,  or  sea-salt.  The  exact  quantities  required  for  mutual  decom- 
position are  296  parts,  or  one  proportion  of  the  bipersulphate,  and  120 
parts,  or  two  proportions  of  the  chloride. 

ACTION  ON  THE  ANIMAL  ECONOMY.*  The  common  appellation  of 
this  substance  indicates  its  corrosive  nature.  It  thus  affects  the 
throat,  stomach  and  intestines,  producing  high  inflammation  and  all  its 
consequences — vomiting,  dysentery,  occasional  inflammation  of  the 
lungs,  or  of  the  urinary  passages.  After  death,  greater  or  less  marks 
of  corrosion,  and  combined  sometimes  with  mortification,  are  no- 
ticed. 

TESTS — In  the  solid  state.  1.  Corrosive  sublimate  sublimes  in  white 
acrid  fumes  on  the  application  of  heat.  2.  Add  to  it  the  solution  of 
the  protochloride  of  tin,  *'  corrosive  sublimate,  when  left  for  some 
time  in  this  solution,  first  becomes  grayish-black,  and  in  no  long  time 
its  place  is  supplied  by  globules  of  mercury,  the  chlorine  being  entire- 
ly abstracted,  by  the  protochloride,  which  consequently  passes  to  the 
state  of  a  bichloride."  This  is  a  beautiful  test,  for  which  we  are  in- 
debted to  Professor  Christison. — Treatise  on  Poisons,  p.  272. 

In  the  fluid  state.  1.  Sulphuretted  hydrogen,  in  sufficient  quanti- 
ty, causes  a  black  precipitate,  the  sulphuret  of  mercury.  2.  The 
protochloride  of  tin  is  a  very  delicate  test.  It  gives  a  white  pre- 
cipitate in  small  quantity,  but  which  darkens  as  more  is  added.  It 
may  be  continued  until  metallic  mercury  is  thrown  down,  as  in  the 
previous  experiment.  3.  Nitrate  of  silver  is  a  good  test  of  the  pre- 
sence of  chlorine,  as  it  throws  down  a  white  precipitate,  the  chloride 
of  silver.  4.  Hydriodate  of  potash  carefully  added,  causes  a  pale 
scarlet  precipitate,  the  iodide  of  mercury.  5.  Mr.  Sylvester's  reduc- 
tion by  means  of  galvanic  electricity.  Let  a  piece  of  gold  be  moist- 
ened with  the  solution,  then  touch  it  through  the  solution  with  a  small 
iron  wire,  an  amalgam  will  be  formed  on  the  gold  in  a  few  seconds. 
The  mercury  thus  metallized  may  be  sublimed  by  placing  the  gold,  (if 
a  ring  or  wire  has  been  used)  in  a  tube,  and  applying  heat  to  the  bot- 
tom.— Orfila. 

REFERENCES.  For  a  detail  of  the  processes  adopted  for  preparing  this 
compound,  consult  the  general  works  quoted  under  the  last  article.  Webster's 
Brande  contains  an  interes'ing  view  of  the  changes  which  take  place  in  the 
substances  employed.  Dr.  Davt/s  experiments  on  the  solibiiity  of  corrosive 
sublimate,  and  the  action  of  light  upon,  it  and  its  solutions,  in  Phil.  Trans. 
1822,  or  Repert.  of  Arts,  2d  ser.  xlii.  348.  On  its  poisonous  effects,  set 
Christison  on  Poisons,  and  Orfda,  in  Annales  D"*  Hygiene,  i.  559. 

*  The  notices  of  the  action  and  tests  of  corrosive  sublimate,  arsenic  and 
tartar  emetic,  were  furnished  entirely  by  my  brother,  Dr.  T.  R.  Beck,  to  whom 
I  AID  also  indebted  for  a  revision  of  all  the  articles  relating  to  toxicology,  con- 
tained in  this  work. 


344  MERCURY. 


MERCURY  AND  BROMINE. 

Mercury  and  bromine  combine  in  two  proportions.  The  first  com- 
pound is  formed  by  the  addition  of  an  alkaline  hydrobromate  to  the 
protonitrate  of  mercury.  The  second  by  bringing  bromine  and  mer- 
cury in  contact — heat  is  evolved,  but  no  light,  and  a  white  bromide  is 
the  result. 


MERCURY  AND  IODINE. 

There  are  two  compounds  of  these  bodies.  The  Protiodide,  con- 
sisting of  one  proportion  of  mercury  and  one  of  iodine,  is  yellow,  and 
is  formed  by  mixing  a  solution  of  the  protonitrate  of  mercury  with 
the  hydriodate  of  potassa.  The  Deiitiodide,  consisting  of  one  propor- 
tion of  mercury  and  two  of  iodine,  is  of  a  very  rich  red  colour,  arid  is 
formed  by  the  action  of  hydriodate  of  potassa  on  any  persalt  of  mer- 
cury. It  forms  a  beautiful  pigment. — A.  A.  Hayes,  SILL  Jour.  xvi. 
174.  —  On  the  medicinal  employment  of  these  compounds,  ste  Mugtndies 
Formulary,  99. 

MERCURY  AND  SULPHUR. 

By  combination  with  sulphur,  mercury  forms  two  distinct  com- 
pounds. 

Protosulphuret  of  Mercury. — Atom.  Num.  216 — Synib.  S+ 

Hg. 

A  black-coloured  substance  which  may  be  converted  into  the  sul- 
phate by  digestion  in  nitric  acid,  and  which,  when  exposed  to  heat,  is 
resolved  into  the  bisulphuret  and  metallic  mercury. 

It  is  prepared  by  transmitting  a  current  of  sulphuretted  hydrogen 
gas  through  a  dilute  solution  of  the  protonitrate  oi' mercury,  or  through 
water  in  which  calomel  is  suspended. 

When  equal  parts  of  sulphur  and  mercury  are  triturated  together 
until  the  metallic  globules  cease  to  be  visible,  a  dark-coloured  mass  re- 
sults, called  Ethiops  Mineral.  It  is  the  Black  Sulphuret  of  Mercury  of 
the  Pharmacopeias,  but  Mr.  Brande  has  proved  it  to  be  a  mixture  of 
sulphur  and  bisulphuret  of  mercuiy. — Brande's  Jour,  xviii.  294. 

Bisulphurct  of  Mercury. — Atom.  Num.  232 — Symb.  2S-f-Hg. 

A  compound  of  a  beautiful  red  colour,  which  when  reduced  to  powder 
forms  the  well  known  pigment  called  Vermilion. 

NATIVE  STATE  AND  PREPARATION.  This  substance  occurs  native,  and 
is  known  by  the  name  of  Cinnabar,  from  which  most  of  the  mercury 
of  commerce  is  obtained  by  distillation  with  iron  filings.  This  com- 
pound is  artificially  prepared  by  fusing  sulphur  with  about  six  times  its 
weight  of  mercury,  and  subliming  in  close  vessels.  It  may  also  be 
obtained  by  mixing  concentrated  solutions  of  corrosive  sublimate  with 
hydro-sulphuret  of  ammonia.  A  brownish  muddy  precipitate  is  ob- 
tained, which,  when  left  undisturbed,  turns  yellow  in  three  or  four 


MERCURY.  345 

days,  then  orange,  and  finally  acquires  a  beautiful  cinnabar  colour. — 
Nicholson's  Jour.  8vo.  i.  299. 

It  has  been  shown  by  H.  Rose,  that  sulphuret  of  mercury  forms 
compounds  in  atomic  proportions  with  the  chloride,  iodide,  bromide 
and  fluoride  of  that  metal. — Ann.  de  Chim.  et  de,  Phys.  xl.  46. 

ADULTERATION.  This  compound  is  sometimes  adulterated  by  red 
lead,  chalk  and  dragon's  blood.  The  former  may  be  detected  by  ex- 
posing the  suspected  vermilion  to  heat  in  an  iron  spoon.  Pure  ver- 
milion will  volatilize  without  residue,  but  if  it  contains  red  lead  it  will 
leave  in  the  spoon  a  brown  powder.  Chalk  may  be  detected  by  mixing 
the  suspected  powder  with  a  little  water  and  adding  nitric  acid.  Effer- 
vesence  will  be  produced  if  any  chalk  is  present,  and  the  solution  may 
be  subsequently  neutralized  with  ammonia  and  treated  with  oxalate  of 
ammonia,  by  which  the  lime  will  be  thrown  down.  If  dragon's  blood 
be  present  it  may  be  detected  by  digesting  the  suspected  vermilion  in 
alcohol,  when  the  solution  will  appear  red. 

REFERENCES.  Berzelms,  Traite  de  Chim.  iii.  112.  Guibourt,  Ann.  de 
Chim.  et  de  Phys.  ii.  425.  The  process  used  by  the  Dutch,  so  celebrated  for 
the  preparation  of  Cinnabar,  is  described  in  Ann.  de  Chim.  iv.  and  Aikirt'g 
Chem.  Diet.  ii.  For  the  process  of  the  Chinese,  see  Brewster^s  Edin.  Jour* 
of  Science,  N.  S.  ii.  352.  Kirchoff  on  the  preparation  of  Cinnabar  in  the 
humid  way,  Repert.  of  Arts,  2d  ser.  xlii.  180. 

Bycianide  or  Bicyanuret  of  Mercury. — Atom.  Num.  252 — 
Symb.  2  (2C-f N.)-fHg. 

PROPERTIES.  This  substance,  when  pure,  is  colourless  and  inodor- 
ous, has  a  very  disagreeable  metallic  taste,  and  is  highly  poisonous  ; 
it  does  not  affect  the  colour  of  litmus  or  turmeric  paper  ;  when  strong- 
ly heated  is  converted  into  cyanogen  and  metallic  mercury  ;  it  is  more 
soluble  in  hot  than  in  cold  water,  and  dissolves  in  that  liquid  without 
change  ;  the  solution  has  not  the  characteristic  odour  of  the  salts  of 
hydrocyanic  acid,  nor  do  alkalies  throw  down  the  oxide  of  mercury. 

PREPARATION.  This  compound  is  best  prepared  by  boiling,  in  any 
convenient  quantity  of  water,  eight  parts  of  finely  levigated  ferrocy- 
anate  of  the  peroxide  of  iron,  quite  pure  and  well  dried  on  a  sand 
bath,  with  eleven  parts  of  the  peroxide  of  mercury,  in  powder,  until 
the  blue  colour  of  the  ferrocyanate  entirely  disappears.  A  colourless 
solution  is  formed,  which,  when  filtered  and  concentrated  by  evapora- 
tion, yields  crystals  of  bicyanuret  of  mercury,  in  the  form  of  quad- 
rangular prisms.  In  this  process,  the  oxygen  of  the  oxide  of  mercury 
unites  with  the  iron  and  hydrogen  of  the  ferrocyanic  acid  ;  while  the 
metallic  mercury  enters  into  combination  with  the  cyanogen. — Turner, 
in  the  Edin.  Jour,  of  Science,  v.  245.  Johnson  on  the  constitution  of 
Cyanide  of  Mercury,  same  icork,  N.  S.  i.  119. 

MERCURY  AND  THE  METALS. 

It  has  already  been  stated,  that  when  mercury  combines  with  other 
metals,  the  resulting  compounds  are  called  amalgams,  (page  203)  and 
some  of  these  substances  have  been  noticed,  (p.  205,  214,  282.) 

A  solid  amalgam  of  lead  and  another  of  bismuth,  on  admixture  to- 
gether, have  the  singular  property  of  instantly  becoming  fluid.  The 


346  MERCURY. 

amalgams  of  gold  and  silver  are  employed  in  gilding  and  plating  ;  and 
the  amalgam  of  tin  and  mercury  is  used  in  the  manufacture  of  com- 
mon mirrors. — For  a  good  description  of  this  process,  see  Bigeloic's 
Technology.  408. 

SALTS    OF    MERCURY. 

Protonitrate  of  Mercury. — A  white  crystalline  salt,  which  has  a  disa- 
greeable taste,  and  is  not  altered  by  exposure  to  the  air  ;  is  only  par- 
tially soluble  in  water,  and  the  solution  affords  black  precipitates,  with 
the  alkalies. 

This  salt  is  best  formed  by  digesting  mercury  in  nitric  acid,  diluted 
with  three  or  four  parts  of  water,  until  the  acid  is  saturated,  and  then 
allowing  the  solution  to  evaporate  spontaneously,  in  an  open  vessel. 
The  solution  always  contains,  at  first,  some  nitrate  of  the  peroxide, 
but  if  metallic  mercury  is  left  in  the  liquid,  a  pure  protonitrate  is  grad- 
ually deposited. 

Mitscherlich  supposes  this  to  be  a  subsalt,  and  obtains  the  neutral 
salt  in  crystals,  by  dissolving  the  former  in  pure  water,  acidulated  with 
nitric  acid,  and  evaporating  spontaneously  without  the  contact  of  me- 
tallic mercury  or  uncombined  oxides. — Ann.  de  Cldm.  et  de  Phys.  xxxv* 
421. 

Peniitratc  of  Mercury. —Atom.  Num.  ZtO—Symb.  (5O+N) 
+  (20+Hg) 

A  beautiful  transparent  and  colourless  salt,  which  crystallizes  in 
rhombic  prisms  :  when  heated  it  becomes  firs.t  opaque,  then  yellow,  and 
is  at  last  dissipated. 

When  this  salt,  which  is  obtained  by  heating  mercury  in  an  excess 
of  strong  nitric  acid,  is  thrown  into  hot  water  it  is  resolved  into  a  sol- 
uble salt,  the  composition  of  which  is  unknown,  and  into  a  yellow  sub- 
salt,  which  is  the  Nitrous  turpeth  of  the  old  writers.  The  latter  was 
found  by  Grouvelle  to  consist  of  one  proportion  of  acid  to  two  of  the 
peroxide.  [Ann.  de  Chim.  et  de  Phys.  xix.]  If  this  is  correct,  it  is  a 
Dipernitrate  of  Mercury.  —  See  Thomson's  First  Prin.  ii.  404. 

Protosulphate  of  Mercury. — Atom.  J\"vm.  266 — S?/w,6.(3O+ 
S)+(0+Hg.)+a  Aq. 

A  salt  occurring  in  fine  white  scaly  crystals,  which  have  little  taste, 
and  redden  vegetable  blues.  It  is  prepared  by  boiling  mercury  in  its 
weight  of  sulphuric  acid. — Thomson's  First  Prin.  ii.  395. 

Persulphate  of  Mercury. — Atom.   Num.  305 — Symb.  2 
'(30+S)+(20+Hg)+9Aq. 

This  salt  is  strictly  Biper sulphate,  and  occurs  in  white  irregular  crys- 
tals. It  is  formed  by  heating  for  some  time  one  part  of  mercury  in 
three  of  sulphuric  acid. 

When  this  salt  is  thrown  into  hot  water,  a  yellow  precipitate,  for* 


MERCURY.  347 

merly  called  Tarpeth  Mineral,  subsides.  According  to  Dr.  Thomson, 
this  last  is  a  true  persulphate,  consisting  of  one  proportion  of  acid  and 
one  of  peroxide  of  mercury.  [First  Prin.  ii.  403.]  The  hot  water 
retains  some  of  the  sulphate  in  solution,  together  with  free  sulphuric 
acid. 

The  principal  use  of  this  salt  is  in  the  preparation  of  corrosive  sub- 
limate and  calomel. 

Protophosphate  of  Mercury.— A  white  tasteless  powder,  insoluble  in 
water,  formed  by  decomposing  nitrate  of  mercury  by  phosphate  of 
soda. 

Prctocarbonate  of  Mercury. — A  white  tasteless  insoluble  powder,  ob- 
tained by  precipitating  a  solution  of  nitrate  of  mercury  by  carbonate 
of  soda. 

Cyanite  of  Mercury?  Fulminating  Mercury. — A  powerful  detonat- 
ing compound  of  mercury,  described  in  the  Philosophical  Transac- 
tions for  1800,  by  Mr.  E.  Howard.  It  is  prepared  by  dissolving  100 
grains  of  mercury  in  a  measured  ounce  and  a  half  of  nitric  acid,  of 
specific  gravity  1*3  ;  and  adding,  when  the  solution  has  become  cold, 
two  ounces  by  measure  of  alcohol,  the  density  of  which  is  0-849. — 
The  mixture  is  then  heated  till  a  moderately  brisk  effervescence 
takes  place,  during  which  the  fulminating  compound  is  generated. 
The  precipitate  which  falls  down  is  to  be  immediately  collected  on  a 
filter,  well  washed  with  distilled  water  and  dried  in  a  heat  not  exceed- 
ing that  of  a  water  bath.  This  powder  has  the  property  of  detonating 
loudly  in  a  gentle  heat,  or  by  slight  friction.  It  sometimes  explodes 
from  such  trifling  causes  that  it  cannot  be  kept  without  danger,  even 
when  secured  from  friction  or  heat.  [See  Henry's  Chem.  ii.  140.]  Ac- 
cording to  Liebig  and  Gay  Lussac,  this  compound  consists  of  oxide  of 
mercury  combined  with  a  peculiar  acid,  which  they  named  the  Ful- 
minic  ;  but  this  is  now  generally  believed  to  be  indentical  with  the  cy- 
anous  acid  of  Wb'hler,  and  if  this  is  correct,  fulminating  mercury  is 
properly  a  cyanite  of  mercury.  (See  p.  1S'2.) 

Chromate  and  Bichromate  of  Mercury. — The  former  exists  in  a  dull 
yellow  powder,  obtained  by  boiling  a  solution  of  ammonia  on  the  bi- 
chromate ;  which  is  of  a  beautiful  scarlet  colour,  and  is  obtained  by- 
adding  chromate  of  potassa  to  the  protonitrate  of  mercury.  See  a  valu- 
able, paper  on  the  combinations  of  Chromium,  by  tf.  A.  Hayes,  in  Silliman'f 
Jour.  xiv.  136,  omitted  under  Chromium. 

REFERENCES.  On  the  Salts  of  Mercury,  see  Donovan's  aper  before  quo 
ted,  and  Thomson's  First  Prin.  ii.  359. 

TESTS  OF  THE  SALTS  OF  MERCURY.  Some  of  these  have  already  been 
noticed  under  corrosive  sublimate.  The  soluble  salts  furnish  white 
precipitates  with  ferrocyanate  ofpotassa,  and  black  with  sulphuret- 
ted hydrogen.  A  plate  of  copper  immersed  into  their  solutions  oc- 
casions the  separation  of  metallic  mercury.  The  insoluble  salts  are 
mostly  entirely  volatilized  at  a  red  heat ;  if  distilled  with  charcoal, 
they  afford  metallic  mercury. 


348  SILVER. 

SECTION  XXXVI. 
SILVER. 

Atom.  Num.  WS.—Symb.  Ag*. — &p.  gr.  10-51. 

PROPERTIES.  This  metal  has  a  beautiful  white  colour  and  great 
lustre,  being  surpassed  in  this  respect  only  by  polished  steel  ;  its  spe- 
cific gravity  when  hammered,  is  10-5,  and  in  malleability  and  ductility 
it  is  only  surpassed  by  gold  ;  when  pure  is  so  soft  that  it  may  be  cut 
with  a  knife ;  it  fuses  at  the  temperature  of  20  J  or  22°  of  Wedge  wood  ; 
is  not  oxidized  by  exposure  to  air  or  moisture,  but  when  exposed  in  a 
state  of  fusion  to  a  current  of  air  or  oxygen  gas.  a  film  of  oxide  is 
formed  on  the  surface,  but  it  parts  with  the  oxygen  spontaneously  as 
it  becomes  solid,  [Lwcas,  in  Manchester  Memoirs,  N.  jSf.  iii.]  a  property 
which  appears  to  belong  only  to  pure  silver.  [Chevillot,  Ann.  de  Chim. 
ct  de  Phys.  xiii.  299.]  According  to  Gay  Lussac,  a  more  advantage- 
ous process  is,  to  throw  small  quantities  of  nitre  upon  silver  retained 
in  fusion  in  a  crucible.  In  about  half  an  hour  the  crucible  is  to  be 
withdrawn  and  plunged  into  water  brought  under  a  bell  glass,  when  a 
large  quantity  of  oxygen  is  disengaged. — Jour,  of  the  Royal  Institution, 
ii.  627. 

NATIVK  STATE  AND  EXTRACTION.  This  metal  frequently  occurs  na- 
tive in  silver  mines,  both  massive  and  in  octahedral  or  cubic  crystals. 
It  is  also  found  in  combination  with  several  other  metals,  such  as  gold, 
antimony,  copper,  and  arsenic,  and  with  sulphur.  Seventeen  different 
ores  of  silver  are  described  by  mineralogists. 

Pure  silver  may  be  obtained  for  chemical  purposes  by  placing  a 
clean  piece  of  copper  in  a  solution  of  the  nitrate  of  silver,  washing 
the  precipitated  metal  with  pure  water,  and  then  digesting  it  in  ammo- 
nia, in  order  to  remove  any  adhering  copper.  It  may  also  be  prepar- 
ed from  the  chloride  of  silver,  either  by  exposing  that  compound  mix- 
ed with  a  pure  or  carbonated  alkali  to  a  strong  heat  in  a  black  lead  cru- 
cible, or  by  transmitting  over  it  a  current  of  hydrogen  gas,  when  heat- 
ed to  redness  in  a  tube  of  porcelain. 

TESTS  OF  PURE  SILVER.  Dissolve  it  in  nitric  acid.  Ft  must  give  no 
black  insoluble  precipitate,  otherwise  it  contains  gold.  If  it  gives  a 
blue  solution  it  contains  copper.  The  solution  formed  by  dissolving 
silver  leaf  in  nitric  acid,  must  not  become  purple  when  mixed  with  a 
solution  of  chloride  of  gold,  otherwise  the  silver  leaf  contains  tin. 

REFEKKNCES.  Donovan,  in  Phil.  Mag.  xlvii.  205.  Thomson's  First 
Prin.  ii.  43(>.  Gay  Lussac  on  the  precipitation  of  Silver  by  Copper,  in  Ann. 
de  Chim.  or  Report,  of  Arts,  2d  set:  xx.  252,  Berzelius,  Trade  de  Chim.  iii. 
88.  Det  Rio  on  the  reduction  of  Silver  Ores  by  the  method  of  BecquercL^ 
Breu-ster's  Edm.  Jour,  of  Science,  N.  8.  v.  222. 

*  From  the  latin  Argentuin. 


SILVER.  349 

SILVER    AND  OXYGEN. 

Oxide  of  Silver.— Mm.  Num.  116 — Symb.  O+Aq. 

This  substance  is  of  an  olive  colour,  insoluble  in  water,  and  taste- 
less ;  when  heated  the  oxygen  is  driven  off,  and  the  metal  is  reduced. 
It  is  prepared  by  adding  lime-water  or  solution  of  pure  baryta  to  solu- 
tion of  nitrate  of  silver,  washing  and  drying  the  precipitate. 

When  this  oxide  of  silver,  recently  precipitated,  is  left  in  contact 
for  ten  or  twelve  hours  with  a  strong  solution  of  ammonia,  the  great- 
er part  is  dissolved,  but  a  black  powder  remains,  which  detonates  vi- 
olently from  heat  or  percussion.  It  appears  to  be  a  compound  of  am- 
monia and  the  oxide  of  silver,  or  of  nitrogen  and  silver.  It  should  be 
made  in  very  small  quantities  and  dried  spontaneously  in  the  air.  See 
Berlhollet,  Ann.  de  (.'him.  i. 

When  a  solution  of  the  oxide  of  silver  in  ammonia  is  exposed  to  the 
air,  its  surface  becomes  covered  with  a  pellicle,  which  Mr.  Faraday 
considers  to  be  a  distinct  oxide  with  less  oxygen  than  the  one  just  de- 
scribed,— an  opinion  which  is  also  confirmed  by  Dr.  Thomson,  who 
calls  it  a  suboxide. — Brande's  Jour.  iv.  270.  Thomson's  First  Prin.  i. 
433. 

SILVER  AND  CHLORINE. 

Chloride  of  Silver.-— Atom.  Num.  14345— Symb.  Cl+Aq. 

PROPERTIES.  This  compound  when  formed  by  precipitation  is  at 
first  quite  white,  but  by  exposure  to  the  direct  solar  rays,  it  becomes 
violet  and  almost  black  in  the  course  of  a  few  minutes,  arid  a  similar 
effect  is  produced  by  diffused  day  light ;  it  is  insoluble  in  water  and 
very  sparingly  dissolved  by  the  stronger  acids,  but  is  soluble  in  ammo- 
nia ;  at  the  temperature  of  about  500°  it  fuses,  and  forms  a  semi- 
transparent  horny  mass  on  cooling,  and  hence  sometimes  called  Horn 
Silver;  bears  the  combined  action  of  heat  and  charcoal  without  de- 
composition, but  is  readily  decomposed  by  hydrogen  gas,  with  the  for- 
mation of  muriatic  acid  ;  it  is  also  rapidly  decomposed  by  tin  and  zinc. 

It  is  decomposed  by  hydrogen  gas. — If  a  few  pieces  of  zinc  be  put  into 
a  test  glass  and  some  dilute  sulphuric  acid  be  poured  over  it,  an  effer- 
vescence takes  place,  and  hydrogen  gas  is  disengaged.  Chloride  of 
silver  placed  above  the  zinc  in  the  same  glass,  is  speedily  reduced  by 
this  hydrogen  and  converted  into  metallic  silver. 

Chloride  of  silver  sometimes  occurs  native  in  silver  mines.  It  is  al- 
ways generated  when  silver  is  heated  in  chlorine  gas,  and  may  be  pre- 
pared conveniently  by  mixing  muriatic  acid,  or  any  soluble  muriate 
with  nitrate  of  silver. 

REFERENCES.  On  the  composition  of  this  substance,  see  Thomson's  First 
Prin.  i.  429;  and  Berzelius,  in  Arm.  of  Phil.  xv.  90.  Faraday  on  the  de- 
composition of  Chloride  of  Silver  by  Hydrogen  and  by  Zinc,  Brandos  Jour. 
viii.  374. 


SILVER  AND  BROMINE. 


Bromide  of  Silver. — A  light  yellow  curdy  sul 
n  exposure  to  light,  is  insoluble  in  water  and  i 


substance  which  blackens 


on  exposure  to  light,  is  insoluble  in  water  and  in  nitric  acid,  but  solu- 


350 


SILVER. 


ble  in  ammonia.     It  is  formed  by  adding  an  alkaline  hydrobromate  to 
a  solution  of  nitrate  of  silver. 

SILVER  AND  IODINE. 

Iodide  and  Silver. — Afom.Nmn.  234 — Symb.  I+Aq. 

A  compound  of  a  greenish  yellow  colour,  insoluble  both  in  water 
and  ammonia,  and  formed  by  mixing  hydriodate  of  polassa  with  ni- 
trate of  silver. 

SILVER  AND  SULPHUR. 

Rulphnret  of  Silver. — Atom.  Num.  124 — Symb.  S-j-Aq. 

A  compound  of  a  black  colour,  capable  of  being1  cut  with  a  knife, 
much  more  fusible  than  the  metal,  and  from  which  "the  sulphur  can  be 
driven  off  by  heat. 

This  substance  often  occurs  native  in  mines,  and  is  the  Silver  Glance 
of  mineralogists.  It  may  be  prepared  by  heating  to  low  redness  thin 
plates  of  silver  with  alternate  layers  of  sulphur.  It  is  also  formed  by 
transmitting  a  current  of  sulphuretted  hydrogen  gas  through  a  solu- 
tion of  nitrate  of  silver. 

Cyanide  of  Silver.— Atom.  Num  134— Symb.  (N-f  2C.)+Aq. 

A  white  curdy  substance,  similar  in  appearance  to  the  chloride  of 
silver,  insoluble  in  water  and  nitric  acid,  and  soluble  in  a  solution  of 
ammonia  ;  is  decomposed  by  muriatic  acid,  with  formation  of  hydro- 
cyanic acid  and  chloride  of  silver.  It  is  formed  by  mixing  hydrocy- 
anic acid  or  an  alkaline  hydrocyanate  with  nitrate  of  silver. 

SILVER  AND  THE  METALS. 

Some  of  the  alloys  of  silver  have  been  noticed  ;  but  the  most  im- 
portant is  the  alloy  of  silver  and  copper,  as  it  constitutes  plate  and 
coin.  The  standard  silver  of  Great  Britain  consists  of  0'90  copper, 
and  11-10  silver.  \_Henry.'}  The  standard  silver  of  the  United  States 
consists  of  1485  of  fine  silver  and  179  parts  of  copper  ;  J3  Troy 
ounces  of  standard  silver  are  coined  into  15  dollars.  This  combina- 
tion, though  its  colour  differs  but  little  from  that  of  pure  silver,  is 
much  harder,  and  is  better  adapted  for  the  purposes  of  coin,  and  of 
domestic  implements.  The  silver  of  commerce  is  composed  of  37  parts 
of  fine  silver  and  3  of  copper. 

Amalgam  of  silver  is  sometimes  employed  for  plating  ;  it  is  applied 
to  the  surface  of  copper,  and  the  mercury  being  evaporated  by  heat, 
the  remaining  silver  is  burnished. 

The  quantity  of  pure  silver  in  any  of  these  alloys  is  determined  by 
the  process  called  cupellation.  This  process  consists  in  exposing  to 
heat  a  clean  piece  of  the  alloy,  of  a  given  weight,  wrapped  up  in  a 
quantity  of  sheet  lead.  This  is  performed  in  a  cupel,  or  shallow  cruci- 
ble made  of  bone  earth,  which  must  be  previously  heated.  The  whole 
is  then  placed  under  a  muffle  and  heated  to  bright  redness  ;  the  metals 


SILVER.  351 

melt,  and,  by  the  action  of  the  air  upon  the  hot  surface,  the  lead  and 
copper  are  oxidized  and  absorbed  by  the  cupel,  and  a  button  of  pure 
silver  ultimately  remains. 

REFERENCES.  The  article  Assay,  in  Aikiti's  Chem.  Diet.  Gray's  Opera. 
tiveCLenist.  Bigelow's  Technology.  Oersted  on  determining  the  composi- 
tion of  Alloys  of  silver,  SfC.  by  the  Magnetic  Needle^  Ann.  de  Chun,  et  de  Phys. 
Nov.  1828.  For  an  analysis  of  different  European  silver  coins,  see  Thom- 
son's Lnorg.  Chem.  i.  638. 

SALTS  OF  SILVER. 

Nitrate  of  Silver.— Atom.  Num.  IW.—Symb.  (5O+N.)     (O 
+Aq.) 

PROPERTIES.  This  salt  is  crystalline,  colourless,  bitter  and  very 
caustic  ;  it  deliquesces  by  exposure  to  air  ;  is  soluble  in  its  own  weight 
of  cold,  and  in  half  its  weight  of  hot  water,  and  in  about  four  times 
its  weight  of  alcohol ;  it  undergoes  igneous  fusion,  when  heated,  and 
assumes,  on  cooling,  the  appearance  of  a  gray  crystalline  mass  ;  at  a 
red  heat  it  is  completely  decomposed,  and  metallic  silver  remains  ;  its 
solution  produces  a  black  stain  upon  the  skin,  and  is  indelible  or  peels 
off  with  the  cuticle  ;  it  may  be  decomposed  by  carbon,  phosphorus  and 
some  of  the  metals. 

It  is  decomposed  by  some  of  the  combustibles, — A  clean  piece  of  phos- 
phorus introduced  into  a  solution  of  nitrate  of  silver,  becomes  cover- 
ed with  a  crust  of  metallic  silver.  This  reduction  is  also  effected  by  a 
clean  plate  of  copper,  and  by  mercury.  In  the  latter  case  the  precipi- 
tation is  slow,  and  produces  a  peculiar  symmetrical  arrangement,  cal- 
led the  Arbor  Diana. 

PREPARATION.  This  salt  is  prepared  by  dissolving  pure  silver  in  ni- 
tric acid,  diluted  with  from  two  to  four  parts  of  water,  and  evapora- 
ting the  solution. 

USES.  Nitrate  of  silver,  when  fused  and  poured  in  this  state  into 
heated  moulds,  forms  the  common  Lunar  Caustic,  or  Lapis  Infernalis, 
employed  by  surgeons  as  a  cautery.  It  is  also  the  basis  of  the  Indeli- 
ble Ink,  used  for  marking  linen  and  cotton,  and  is  sometimes  employed 
for  giving  a  black  colour  to  the  hair,  but  for  this  purpose  it  should  be 
used  with  caution.  In  the  laboratory  it  is  used  as  a  test  of  chlorine 
and  muriatic  acid.* 

REFERENCES.  Bradenbourg  on  making  pure  Nitrate  of  Silver  from  an 
Alloy  of  Silver  and  Copper.  Ann.  of  Phil.  xv.  389.  For  the  mode  of  ol~ 
t  aining  Arbor  Di  >nce,  see  Webster's  Brandt ;  and  for  another  process,  which 
consists  in  suspending  a  small  knot  of  fine  linen  containing  Quicksilver,  in 
/.he  Nitric  Solution  of  Mercury  and  Silver,  see  Repert.  of  Arts,  2d  ser  xvii. 
381.  For  a  notice  of  the  method  of  copying  engravings,  fyc.  by  nitrate  of 
silver,  by  T.  IVedgewood,  see  Paris'  Life  of  Davy.  i.  161. 

*  The  fo' low  ing  singular  fact  is  stated  by  Sir  John  Herschel  in  his  Dig- 
course  on  the  Study  of  Natural  Philosophy.  A  solution  of  nitrate  of  silver 
and  another  of  hyposulphite  of  soda,  have  each  of  them  separately,  whe»i 
taken  into  the  mouth,  a  disgusting  bitter  taste ;  but  if  they  be  mixed,  or  if  one 
be  tasted  before  the  mouth  is  thoroughly  cleared  of  the  other,  the  sensible  im- 
pression is  that  of  intense  sweetness. 


352  SILVER. 

Fulminating  Silver. — Besides  the  fulminating  compound  of  silver, 
formed  by  the  addition  of  ammonia  to  the  nitrate  of  silver,  another 
one  is  formed,  by  a  process  similar  to  that  noticed  under  fulminating 
mercury,  viz.  by  adding  alcohol  to  a  solution  of  silver  in  nitric  acid. 
Its  preparation  requires  great  caution.  The  same  views  are  entertain- 
ed concerning  its  composition  as  concerning  that  of  fulminating  mer- 
cury. It  is  probably  a  Cyanite  of  Silver. — For  details  concerning  its 
preparation,  fyc.  see,  Henry's  Chem.  or  Webster' s  Brande — and  for  some 
new  views  concerning  it,  see  Dr.  Ellet's  Essay  upon  the  compounds  of 
Cyanogen,  Sill.  Jour,  xviii.  335.  See  also  a  Report  on  the  Fulminating 
Powders,  capable  of  being  used  as  Priming  for  Fire  Arms,  by  MM.  Au- 
oert,  Pelissier  and  Gay  Lussac,  in  which  the  preference  is  given  to  Fulmi- 
nating Merciiry,  Ann.  de  Chim.  xlii.  or  Repert.  of  Pat.  Invent,  ix.  182 
307. 

Sulphate  of  Silver.— Atom.    Num.  156—  Symb.   (3O+S)+ 
(0+Aq.) 

v>  PROPERTIES.  A  white  powder  with  a  metallic  taste  ;  when  heated  it 
melts  and  is  decomposed,  being  changed  into  sulphurous  acid,  oxygen 
and  metallic  silver ;  soluble  in  about  88  times  its  weight  of  boiling 
water,  and  when  the  solution  cools,  the  salt  is  partly  deposited  in  the 
state  of  small  needles. — Thomson's  First  Prin.  ii.  406. 

This  salt  may  be  obtained  by  digesting  sulphuric  acid  over  oxide  of 
silver,  or  by  mixing  together  concentrated  solutions  of  nitrate  of  sil- 
ver and  sulphate  of  soda.  It  is  the  proper  test  for  ascertaining  the 
presence  of  muriatic  acid  where  sulphuric  acid  is  also  supposed  to  be 
present,  for  the  nitrate  of  silver  precipitates  both  these  acids. 

There  is  also  a  Hyposulphite  and  a  Sulphite  of  Silver,  obtained  by 
processes  similar  to  those  already  described. 

Phosphate  of  Sifaer. — This  salt  is  obtained  by  adding  solution  of 
phosphate  of  soda  to  solution  of  pure  nitrate  of  silver,  washing  and 
drying  the  precipitate.  It  is  in  the  form  of  a  yellow  powder,  fusible 
at  a  red  heat  without  any  farther  loss  of  weight.  It  appears  to  be  a 
subphosphate. — Thomson  s  First  Prin.  ii.  408. 

Carbonate  of  Silver.— Atom.  Num.  13S—Symb.  (2O+C)+ 
(0+Ag.) 

A  white  insoluble  powder,  with  a  slight  shade  of  blue,  which  black- 
ens by  exposure  to  light,  and  effervesces  with  dilute  nitric  acid.  It  is 
formed  by  adding  carbonate  of  potassa  to  nitrate  of  silver.  Carbonate 
of  ammonia  only  throws  down  a  portion  of  the  silver  from  the  nitrate,, 
and  forms  a  triple  Ammonio-  Carbonate  of  Silver. 

Chromate  of  Silver,  is  precipitated  of  a  crimson  colour  by  adding" 
chromate  of  soda  to  nitrate  of  silver.  It  soon  loses  its  brilliant  tint 
and  becomes  brown, — Phil.  Mag.  and  dnn,  i.  345. 

REFERENCES.  On  the  Salts  of  Silver,  see  Thomson's  First  Prin  ii« 
404.  Pro-list1  s  facts  relating  to  the  chemical  history  of  Silver,  Jour,  de  Phy&\ 
or  Repert.  of  Arts,  2d  ser.  ix.  310,  355. 

TESTS  OF  THE  SALTS  OF  SILVER.  Those  which  are  soluble  are  recog- 
nized by  furnishing  a  white  precipitate  with  muriatic  acid,  which  black- 
ens by  exposure  to  light,  and  which  is  readily  soluble  in  ammonia,  and 


GOLD.  353 

by  affording  metallic  silver  upon  the  immersion  of  a  plate  of  copper. 
The  salts  insoluble  in  water  are  soluble  in  liquid  ammonia,  and  when 
heated  on  charcoal,  before  the  blow-pipe,  they  afford  a  globule  of  silver. 

SECTION  XXXVI. 
GOLD. 

Atom.  Num.  200—  Symb.  Au.*  Sp.  gr.  19-3. 

PROPERTIES.  This  metal,  whose  history  and  principal  uses  are  sim- 
ilar to  those  of  silver,  has  an  orange-yellow  or  reddish-yellow  colour, 
and  may  be  made  to  assume  a  high  lustre,  only  inferior  to  steel,  silver 
and  mercury  ;  exceeds  all  other  metals  in  malleability  and  ductility, 
(see  page  196,)  but  is  less  tenacious  than  several  other  metals  ;  is  not 
changed  by  exposure  to  air  and  moisture  for  any  length  of  time,  nor 
oxidized  by  being  kept  in  a  state  of  fusion  in  open  vessels  ;  it  is  not 
acted  on  by  any  of  the  pure  acids,  however  concentrated,  its  only 
solvents  being  chlorine  and  nitro-muriatic  acid ;  the  effect  being  in 
both  cases  ascribed  to  the  agency  of  chlorine,  (see  page  135,) ;  it  is 
exceedingly  soft  and  flexible  when  pure  ;  is  less  fusible  than  silver,  re- 
quiring a  heat  of  32"*  of  Wedgewood  for  its  fusion. 

NATIVE  STATE  AND  PREPARATION.  Gold  occurs  in  nature  in  a  metallic 
state,  either  pure  or  in  combination  with  other  metals.  It  occurs  mas- 
sive, capillary,  in  grains,  and  crystallized  in  cubes  and  octahedrons. 
It  is  most  frequently  found  in  alluvial  soils  and  in  the  beds  of  certain 
rivers,  especially  those  of  the  west  coast  of  Africa  and  Peru,  Brazil 
and  Mexico.  It  is  also  found  in  various  parts  of  Europe  and  of  North 
America,  especially  in  North  Carolina. 

This  metal  may  be  obtained  pure  by  dissolving  standard  gold  in  ni- 
tromuriatic  acid,  evaporating  the  solution  to  dryness.  redissolving  the 
dry  mass  in  distilled  water,  filtering  and  adding  to  it  a  solution  of  pro 
tosulphuret  of  iron  ;  a  black  powder  falls,  which,  after  having  been 
washed  with  dilute  muriatic  acid  and  distilled  water,  affords  on  fusion 
a  button  of  pure  gold. — Vauquelin. 

REFERENCE.  Olmstexd's  account  of  the  Gold  Mines  of  North  Carolina, 
Sill.  Jour.  ix.  5 ;  and  for  other  localities  see  Clcaveland's  Mineralogy. 

GOLD  AND  OXYGEN. 

Oxides  of  Gold. 

There  is  still  much  uncertainty  concerning  the  compounds  of  gold 
and  oxygen.  Berzelius  is  of  opinion  that  there  are  three,  but  their 
composition  is  not  yet  understood.  The  only  well  known  oxide  is 
that  which  is  supposed  to  exist  in  the  solution  of  gold,  combined  with 
muriatic  acid.  According  to  M.  Pelletier,  the  best  method  of  forming 
it  is  by  digesting  the  muriate  with  pure  magnesia,  washing  the  pre- 
cipitate with  water,  and  removing  the  excess  of  magnesia  by  dilute 
nitric  acid.  This  is  probably  a  peroxide,  consisting  of  three  atoms  of 
oxygen  and  one  atom  of  gold. — Berzelius,  Javal,  and  Thomson. 

*  From  the  latin  Aurum» 


354  QOLD. 

The  Peroxide  of  Gold  is  yellow  in  the  state  of  hydrate,  and  nearly- 
black  when  pure  ;  is  insoluble  in  water,  and  completely  decomposed 
by  solar  light  or  a  red  heat ;  it  is  readily  soluble  in  muriatic  acid, 
yielding  the  common  solution  of  gold,  but  it  forms  no  definite  com- 
pound with  any  acid  which  contains  oxygen  ;  it  has  a  very  feeble 
affinity  for  nitric  and  sulphuric  acids,  but  combines,  on  the  contrary, 
with  alkaline  bases,  such  as  potassa  and  baryta,  apparently  forming 
regular  salts,  in  which  it  acts  the  part  of  a  weak  acid.  Hence  Pelle- 
tier  proposes  the  term  Auric  Acid  for  the  peroxide  of  gold,  and  to  its 
compounds  with  the  alkalies  he  gives  the  denomination  of  Anrates. 

Fulminating  Gold. — The  peroxide  of  gold  is  thrown  down  of  a  yel- 
low colour,  by  ammonia,  and  the  precipitate  is  an  aurate  of  that  alkali. 
It  is  a  highly  detonating  compound,  analogous  to  the  fulminating  sil- 
ver described  in  the  last  section. 

REFERENCES.  Proust's  facts  relating  to  the  chemical  history  of  Gold, 
Jour,  ae  Phya.  or  Re.pert.  of  Arts,  2d  ser.  ix.  289,  350.  Pelletier,  Ann.  (If 
Chim.  et  (lc  Phys.  xv.  or  Brandos  Jour.  x.  117.  Vauqueliii's  experiments 
on  some  preparations  of  Gold,  Ann.  de  Chim.  and  Repert.  of  Arts,  °Ld  ser. 
XX  243.  Oberkainpfs  memoir  on  various  combinations  of  Gold,  Arm.  de 
Chim.  Ixxx.,  or  Repert.  of  Arts,  Zd  ser.  xxi.  181,  2-19.  Berzetius,  Traite  dt 
Chim.  iii.  1,  Javal,  Ann*  de  Chim.  el  de  Phys.  xvii.  337,  or  Brande's  Jour. 
xii.  318.  Thomson^  in  first  Prin.  and  Phil.  Mag.  and  Ann.  vii.  4M. 


GOLD    AND    CHLORINE. 

The  same,  degree  of  uncertainty  exists  with  regard  to  the  chlorides , 
as  to  the  oxides  of  gold.  Gold  leaf  introduced  into  chlorine  gas  taket* 
fire  and  burns  ;  and  if  it  be  suspended  in  water,  into  which  the  gas 
is  passed,  it  is  dissolved,  and  the  solution  may  be  concentrated  by 
evaporation.  The  solution  obtained  in  the  manner  directed  in  the 
last  article,  consists  also,  most  probably,  of  the  same  Perchloride.  By 
exposure  to  moderate  heat,  it  parts  with  two-thirds  of  its  chlorine,  and 
is  converted  into  a  yellow  insoluble  Protochloride 

Chloride  of  gold  is  capable  of  combining  with  other  chlorides.  The 
resulting  compounds  are  called  Chloroaurates ,  and  have  been  examined 
by  Bonsdorf. — See  Thomson's  Inorg.  Chem.  ii.  831. 

The  solution  of  gold  is  decomposed  by  substances  which  have  a 
strong  affinity  for  oxygen.  On  adding  protosulphuret  of  iron,  dis- 
solved in  water,  the  iron  is  oxidized  to  a  maximum,  and  a  copious 
brown  precipitate  subsides,  which  is  metallic  gold  in  a  state  of  per- 
fect purity.  A  similar  reduction  is  effected  by  most  of  the  metals, 
and  by  sulphurous  and  phosphorous  acids.  So  when  a  piece  of  char- 
coal is  immersed  in  the  solution  of  gold,  and  exposed  to  the  direct 
solar  rays,  its  surface  acquires  a  coating  of  metallic  gold  ;  and  ribands 
may  be  gilded  by  moistening  them  with  a  dilute  solution  of  goldr 
and  exposing  them  to  a  current  of  hydrogen  or  phosphuretted  hydro- 
gen gas. 

When  a  strong  aqueous  solution  of  gold  is  shaken  in  a  phial  with  an 
equal  volume  of  pure  ether,  two  fluids  result,  the  lighter  of  which  is 
an  Etherial  Solution  of  Gold.  From  this  liquid,  flakes  of  metal  are  de- 
posited on  standing,  especially  by  exposure  to  light,  and  substance^ 
moistened  with  it  receive  a  coating  of  metallic  gold. 

When  the  protomuriate  of  tin  is  added  to  a  dilute  aqueous  solution 


GOLD.  355 

of  gold,  a  purple  coloured  precipitate,  called  the  Purple  of  Cassius,  is 
thrown  down,  which  is  the  substance  employed  in  painting  on  por- 
celain for  giving  a  pink  colour.  It  appears  to  be  a  compound  of  the 
peroxide  of  tin  and  the  purple  oxide  of  gold,  in  which  the  former  is 
supposed  to  act  as  an  acid. 

REFERENCES.     For  experiments  on  the  revival  of  Gold,  see  Mrs.  Fulham-e 
on 

or  his   Essays, 

393,  and  also  the  papers  of  Proust  and  Oberkampf,  quoted  under  the  last  arti- 
cle.    Johnston  on  the  double  Chlorides  of  Gold,  Biewste^s  Edin.  Jour.  N. 
iii.  131,  2BO. 


on  Combustion,  and  Count  RamfortFs  paper  in  Phil.   Trans,  for  1798,  449, 
or  his   Essays.      Dr.  Clarke  on  the  Purple  of  Cassias,  Ami.   of  Phil.   xvii. 


Bromide  of  Gold.— Balard  observed  the  solubility  of  gold  in  bro- 
mine ;  and  Lampadius  found  that  the  dry  compound  is  constituted  of 
equal  parts  of  gold  and  bromine.  It  is  of  a  grayish  black  colour,  is 
soluble  in  water,  and  gives  a  deep-red  liquid,  which  yields  crystallized 
hydrobromate  of  gold  by  evaporation.  The  colour  of  this  salt  is  so  in- 
tense, that  a  single  grain  communicates  a  perceptible  tint  to  5,000 
grains  of  water. — Brande's  Jour.  N.  S.  iii.  489. 

Iodide  of  Gold,  may  be  obtained  by  acting  on  oxide  of  gold  with  hy- 
driodic  acid,  or  by  mixing  chloride  of  gold  with  hydriodate  of  potassa, 
and  washing  and  drying  the  precipitate.  It  is  insoluble  in  cold  water, 
and  very  sparingly  soluble  in  hot.  It  is  decomposed  by  heated  nitric 
or  sulphuric  acids,  which  reduce  the  gold  and  set  iodine  at  liberty. 
It  consists,  according  to  Pelletier,  of  one  proportion  of  each  of  its 
elements. 

Sulphuret  of  Gold. — Sulphur,  even  when  assisted  by  heat,  has  no 
action  on  gold;  but  when  a  current  of  sulphuretted  hydrogen  is  pass- 
ed through  a  solution  of  that  metal,  a  black  precipitate  is  formed, 
which  is  a  true  sulphuret  of  gold.  The  sulphur  may  be  easily  expelled 
from  this  combination  by  heat.  It  appears  to  be  composed  of  one  pro- 
portion of  gold  and  three  proportions  of  sulphur. 

Phosphuret  of  Gold. — This  compound  may  be  obtained  by  passing  a 
atreamof  phosphuretted  hydrogen  through  a  solution  of  gold.  It  has  a 
gray  colour  and  metallic  lustre. 

GOLD    AND    THE    METALS. 

Gold  combines  with  most  of  the  metals.  Antimony,  tin,  zinc  and 
lead,  when  alloyed  with  gold,  destroy  or  impair  its  malleability.  It 
is  stated  that  even  the  fumes  of  antimony  in  the  neighborhood  of  melt- 
ed gold,  are  sufficient  for  this  purpose. 

With  copper,  (standard  gold,)  the  alloy  is  perfectly  ductile  and 
malleable,  but  harder  than  pure  gold,  and  resists  wear  better  than  any 
alloy  except  that  with  silver.  The  sterling  or  standard  gold  of  Great 
Britain,  consists  of  gold  alloyed  with  one-twelfth  its  weight  of  cop- 
per, or  a  mixture  of  both,  as  is  most  common,  and  according  to  Mr. 
Hatchett,  the  average  of  its  specific  gravity  is  17-5.  The  standard 
gold  of  the  United  States  consisis  of  nearly  the  same  proportions  of 
gold  and  alloy.  (For  a  table  of  the  specific  gravity  of  various  gold 
pieces,  see  Hatchett' s  paper,  or  Thomson's  Jnorg.  Chem.) 

The  degree  of  purity  of  gold  is  expressed  by  the  number  of  parts 
contained  in  24  parts  of  any  mixture.  Thus  gold,  in  which  24  such 


356  PLATINUM. 

parts,  (termed  carats  )  contains  22  of  the  pure  metal,  is  said  to  be  22 
carats  fine.  Absolutely  pure  gold,  using  the  same  language,  is  24  car- 
ats fine  ;  and  gold  alloyed  with  an  equal  weight  of  another  metal,  12 
carats  fine. 

The  process  of  water  gilding  consists  in  applying  an  amalgam  of 
gold  to  the  surface  of  silver,  and  driving  off  the  mercury  by  heat.  In 
gilding  porcelain,  Gold  Powder,  obtained  by  the  decomposition  of  the 
chloride,  is  commonly  employed.  It  is  applied  with  a  pencil,  and 
burnished  after  having  been  exposed  to  the  heat  of  a  porcelain  fur- 
nace. 

REFERENCES.  Aikirfs  Diet.  art.  Gold,  contains  an  account  of  the  methods 
of  purifying  gold,  fyc.  Lewis'  Philosophical  Commerce  of  tJie  Arts.  Hatch, 
ett  on  the  various  alloys,  specific  gravity  and  comparative  icear  of  Gold. 
Phil.  Trans.  1803,  abridged  in  Repert.  of  Arts,  Id  ser.  iv.  12.  The  art' 
Gilding,  in  Edin.  Encyclopedia.  The  art.  Coinage,  hy  R.  Mushet,  in  Sup. 
to  the  Ency.  Britamiica.  Bigeloufs  Technology.  For  a  minute  account  of 
the  mode  of  making  gold  leaf  and  gilt  wire,  see  Keaumhr's  Mem.  Paris.  1713, 
p.  199,  and  Leivis'1  Philosophical  Commerce. 

SECTION  XXXVII. 

PLATINUM. 
Atom.  Num.  98*6.— Symb.  Pt.—Sp.  gr.  21-5. 

This  valuable  metal,  discovered  by  Wood  in  1741,  is  found  in  vari- 
ous parts  of  South- America,  in  the  form  of  rounded  or  flattened  grains, 
mixed  with  sand  and  other  alluvial  depositions  ;  and  in  the  province 
of  Antioquia,  in  veins  associated  with  gold.  Rich  mines  of  gold  and 
platinum  have  also  been  recently  discovered  in  the  Uralian  mountains. 
—~Edin.  Jour,  of  Science,  v. 

PROPERTIES.  Pure  platinum  has  a  white  colour  very  much  like  sil- 
ver, but  of  inferior  lustre  ;  it  is  the  heaviest  of  known  metals  ;  its  mal- 
leability is  considerable,  though  far  less  than  gold  and  silver  ;  it  maybe 
drawn  into  wires,  the  diameter  of  which  does  not  exceed  the  2000th 
part  of  an  inch  ;  it  is  a  soft  metal,  and,  like  iron,  admits  of  being  weld- 
ed at  a  high  temperature  ;  it  is  a  less  perfect  conductor  of  caloric  than 
most  other  metals ;  it  undergoes  no  change  from  the  combined  agency 
of  heat  and  air,  and  may  be  exposed  to  the  strongest  heat  of  a  smith's 
forge  without  being  oxidated  or  fused  ;  is  not  attacked  by  any  of  the 
pure  acids,  its  only  solvent  being  chlorine  and  nitromuriatic  acid. 

REFERENCES.  Dr.  \Vollaston?  s  process  for  obtaining  pure  Platinum,  ren- 
dering it  malleable,  fyc.  Phil.  Trans.  li>29,  or  Frankliifs  Jour.  N.  S.  iv.  226. 
For  a  notice  of  the  Gold  and  Platinum  district  in.  Russia,  see  the  Jour,  of  the 
Royal  Institution.,'}.  418.  Coinage,  fyc. ,  of  Russian  Platinum,  Edin.  New 
Phil.  Jour.  iii.  276,  vi.  1^«7.  The  Russian  method  of  rendering  platinum  mal- 
leable is  described  by  W.  Marshall,  in  the  Repertory  of  Patent  Inventions,  xlif. 
397. 


PLATINUM.  357 


PLATINUM    AND    OXYGEN. 

According  to  Berzelius,  there  are  two  oxides  of  platinum,  the  oxy- 
gen of  which  is  in  the  ratios  of  1  to  2.  The  protoxide  is  of  a  black  co- 
lour, reduced  by  a  red  heat,  and  prepared  by  the  action  of  potassa  on 
the  protochloride  of  platinum.  It  probably  consists  of  one  atom  of 
oxygen  and  one  of  platinum.  The  peroxide  has  not  been  obtained  pure, 
but  is  supposed  by  Berzelius  to  exist  in  the  muriate  of  platinum  com- 
bined with  muriatic  acid. 

Dr.  Davy  has  described  a  third  oxide,  intermediate  between  the  per- 
oxide and  the  protoxide,  [P/u/.  Trans,  for  1820,]  and  Mr.  Copper  has 
also  described  what  he  calls  a  Suboxide,  [Brande's  Jour.  iii.  119,]  but 
this  cannot  be  regarded  as  a  definite  compound. 

PLATINUM  AND    CHLORINE. 

Perchloride  of  Platinum  is  procured  by  evaporating  the  solution  of 
platinum  in  mtro-miiriatic  acid,  to  dryness  at  a  gentle  heat.  It  is  de- 
liquescent, and  is  soluble  in  water,  alcohol  and  ether.  The  ethereal 
solution  is  decomposed  by  the  agency  of  light,  metallic  platinum  be- 
ing deposited. 

The  chloride  probably  consists  of  one  proportion  of  platinum  and 
two  proportions  of  chlorine.  When  strongly  heated  it  is  converted 
into  the  Protochloride. 

The  chlorides  of  platinum  combine  with  other  chlorides  and  with 
the  muriate  of  ammonia  and  form  a  class  of  compounds  called  C/tloro- 
platinaf.es,  which  have  been  investigated  by  Bonsdorf.  —[See  Thomson's 
Inorg.  Chem.  ii.  833.] — When  a  solution  of  sal  ammoniac  is  added  to 
a  liquid  chloride  of  platinum,  a  beautiful  orange-yellow  precipitate 
falls,  consisting  of  one  atom  of  the  bichloride  of  platinum-f-one  atom 
muriate  of  ammonia.  When  this  compound,  which  is  commonly  call- 
ed the  muriate  of  platinum  and  ammonia,  is  heated  to  redness,  chlorine 
and  muriate  of  ammonia  are  evolved,  and  pure  platinum  remains  in  the 
form  of  a  delicate  spongy  mass,  which  causes  a  jet  of  hydrogen  to  in- 
flame, (p.  Ill,)  and  which  kindles  an  explosive  mixture  of  hydrogen 
and  oxygen  gases.  Various  contrivances  for  the  purpose  of  producing 
instantaneous  light,  upon  this  principle,  are  now  adopted.  Dr.  Hare 
states  that  if  asbestos  or  charcoal  be  soaked  under  an  exhausted  re- 
ceiver in  muriate  of  platinum,  then  dried  in  an  evaporating  oven  for 
twenty-four  hours,  and  afterwards  ignited,  the  property  of  ignition  in 
the  gaseous  elements  of  water  is  acquired. — Silliman' s  Jour,  xx.  160. 

The  Bichloro-platinate  of  Potassium,  is  obtained  by  adding  pure  po- 
tassa or  a  salt  of  potassa  to  a  concentrated  solution  of  chloride  of  pla- 
tinum. It  consists  of  very  small  octahedrons,  very  little  soluble  in 
water  and  not  at  all  in  alcohol.  When  heated  it  gives  out  chlorine  and 
leaves  a  mixture  of  platinum  and  chloride  of  potassium.  The  proper- 
ty of  forming  this  compound  with  potassa  distinguishes  platinum  from 
all  other  substances. 


358  PLATINUM. 


PLATINUM    AND    SULPHUR. 

Sulphuret  of  Platinum.— When  sulphuretted  hydrogen  gas  is  trans- 
mitted through  a  solution  of  muriate  of  platinum,  a  black  precipitate 
is  thrown  down,  which  Vauquelin  regards  as  a  hydrosulphuret  of  the 
oxide  of  platinum.  It  absorbs  oxygen  from  the  air  while  in  a  moist 
state,  giving  rise  to  the  formation  of  sulphuric  acid.  Its  composition 
has  not  been  determined  with  accuracy. 

A  black  sulphuret  of  platinum  was  procured  by  Mr.  E.  Davy,  by 
heating  the  rnetal  with  sulphur  ;  and  Vauquelin  obtained  a  similar 
compound  by  igniting  the  yellow  muriate  of  platinum  and  ammonia, 
with  twice  its  weight  of  sulphur.  According  to  the  analysis  of  these 
chemists,  it  contains  about  16  per  cent,  of  sulphur.  —  Turner. 

Sulphate  of  Platinum. — The  hydrosulphuret  of  platinum  is  convert- 
ed by  the  action  of  nitric  acid  into  a  sulphate  which  possesses  remark- 
able properties.  On  boiling  it  in  strong  alcohol,  a  black  powder  is 
precipitated,  which  consists,  according  to  Mr.  E.  Davy,  of  96  per  cent, 
of  platinum,  together  with  a  little  oxygen,  nitrous  acid,  and  carbon, 
the  last  of  which  is  supposed  to  be  accidental.  When  this  powder  is 
placed  on  bibulous  paper  moistened  with  alcohol,  a  strong  action  ac- 
companied with  a  hissing  noise  ensues,  and  the  powder  becomes  red 
hot,  and  continues  so  until  the  alcohol  is  consumed.  The  substance 
which  remains  is  pure  platinum. — E.  Davy,  Phil.  Trans.  1820. 

Fulminating  Platinum  may  be  prepared  by  the  action  of  ammonia  m 
slight  excess  on  a  solution  of  sulphate  of  platinum.  It  is  analogous 
to  the  detonating  compounds  which  ammonia  forms  with  the  oxides  of 
of  gold  and  silver. -E.  Davy,  in  Phil.  Trans.  1817. 

PLATINUM    AND    THE    METALS. 

Platinum  combines  with  other  metals  and  forms  alloys  which  are 
not  in  general  characterized  by  useful  properties.  Its  affinity  for  lead 
is  strikingly  shown  by  the  following  experiment  :  If  a  piece  of  lead 
foil,  and  another  of  platinum  foil,  of  equal  dimensions,  be  rolled  up 
together,  and  the  flame  of  a  candle  be  cautiously  directed  by  a  blow- 
pipe towards  the  edges  of  the  rolls,  at  about  a  red  heat,  the  two  metals 
will  combine  with  a  sort  of  explosive  force,  scattering  their  melted 
particles  and  emitting  light  and  heat  in  a  surprising  manner.  [Ann.  of 
Phil.  xiv.  230.]  A  small  bit  of  tin.  zinc  or  antimony,  rolled  in  plati- 
num leaf,  and  treated  in  like  manner,  exhibits  similar  phenomena. — 
[Henry,  ii.  172.]  When  alloyed  with  the  more  oxidable  metals,  it  is 
remarkable  that  platinum  becomes  soluble  in  nitric  acid,  which  has  no 
action  on  the  pure  metal. 


PALLADIUiM — RHODIUM.  359 

SECTION  xxxviii. 

PALLADIUM. 
Atom.  Num.  53 — Symb.  Pd.—  Sp.  gr.  11-5. 

This  metal  was  discovered  by  Dr.  Wollaston  in  1803,  in  an  ore  of 
platinum. 

PROPERTIES.  Palladium  resembles  platinum  in  colour  and  lustre  : 
it  is  both  malleable  and  ductile  ;  is  harder  than  wrought  iron  ;  its 
point  of  fusion  is  intermediate  between  gold  and  platinum  ;  is  dissi- 
pated in  sparks  when  intensely  heated  by  the  compound  blow-pipe  ;  it 
is  oxidized  and  dissolved  by  nitric  acid,  and  by  the  aid  of  heat  is  also 
acted  on  by  sulphuric  and  muriatic  acids,  though  its  proper  solvent  is 
the  nitro-muriatic. 

This  metal  is  obtained  by  adding  to  a  neutral  solution  of  the  ore  of 
platinum,  a  solution  of  bycyariide  of  mercury  ;  and  heating  to  redness 
the  yellowish  white  flocculent  precipitate  of  cyanide  of  palladium, 
which  is  gradually  deposited. 

Oxide  of  Palladium.— Jltom.  Num.  61  —  Symb.  O+Pd. 

When  potassa  is  added  to  solution  of  palladium,  an  orange-colour- 
ed hydrate  is  thrown  down,  which  becomes  black  when  dried,  and  is 
decomposed  by  a  red  heat.  This  oxide  forms  beautiful  red  coloured 
salts,  from  which  metallic  palladium  is  precipitated  by  protosulphate 
of  iron,  and  by  all  the  metals  described  in  the  foregoing  sections,  ex- 
cepting silver,  gold  and  platinum. 

Berzelius  describes  two  oxides  of  palladium,  and  a  sulphuret,  phos- 
phuret  and  carburet. — Traitede  Chim.  iii.  75. 

REFERENCES.  Wollaston,  in  Phil  Trans.  1804  and  1805.  Vauqudins 
Memoir  on  Palladium  and  Rhodium.,  Ann.  de  Chim.  Ixxxviii.  167;  or  Ann 
ef  Phil.  iv.  216. 

SECTION  XXXIX. 
RHODIUM. 

Jltom.  Num.  52 — Symb.  R.—Sp.  gr.  11. 

This  metal,  discovered  by  Dr.  Wollaston  about  the  same  time  as 
the  last,  has  only  been  procured  in  very  minute  quantities  from  the  so- 
lutions of  crude  platinum,  in  the  form  of  a  black  powder,  which  re- 
quires the  strongest  heat  of  a  wind  furnace  for  its  fusion,  and  when 
fused  has  a  white  colour  and  metallic  lustre  ;  it  is  hard  and  brittle,  and 
its  specific  gravity  is  about  11  ;  in  its  pure  state  is  not  attacked  by 
any  of  the  acids,  but  when  alloyed  with  other  metals,  is  oxidized  and 


360  OSMIUM — IKIDIUM. 

dissolved  by  the  nitro-muriatic  acid  ;  it  is  oxidized  by  ignitibn  with 
nitre. 

Oxides  of  Rhodium. — Two  compounds  of  rhodium  and  oxygen  are 
described.  The  Protoxide,  consisting  of  one  atom  of  each  of  the  ele- 
ments is  black.  The  Peroxide,  which  is  the  bases  of  the  salts  of  rho- 
dium, is  of  a  yellow  colour  ;  and  all  these  salts  are  either  red  or  yel- 
low, and  the  muriate  is  a  rose  red. — See  the  references  under  the  last 
Section. 

SECTION  XL. 

OSMIUM. 
Atom.  Num.  99  ?—Symb.  Os.  Sp.  gr.  10. 

This  metai  was  discovered  by  Mr.  Tennant  in  1803,  in  the  black 
powder  left  after  the  digestion  of  crude  platinum  in  nitro-muriatic 
acid.  Osmium  is  separated  from  the  iridium  which  this  powder  also 
contains,  by  alternate  and  frequent  digestions  in  soda  and  muriatic 
acid.  It  can  only  be  obtained  as  a  metal  in  a  disintegrated  state  ;  it 
is  capable  of  supporting  a  white  heat,  without  being  volatilized  or 
fused  ;  it  is  of  a  dark  gray  or  blue  colour  ;  if  ignited  in  open  vessels, 
with  access  of  air,  it  is  oxidized  and  then  dissipated  in  vapour.  On 
agitating  the  metal  with  mercury,  an  amalgam  is  formed,  and  with 
copper,  silver  and  gold,  it  forms  malleable  alloys. 

The  pure  Oxide  of  Osmium  is  soluble  in  water  and  volatile  ;  it  emits 
a  peculiar  odour,  which  has  something  of  the  pungency  of  chlorine. 
The  aqueous  solution  is  colourless,  and  when  shaken  with  mercury,  is 
decomposed,  soon  loses  its  smell  and  forms  an  amalgam. 

Berzelius  has  recently  examined  this  metal  and  its  compounds — and 
has  described  five  oxides  and  sulphurets  and  four  chlorides. 

SECTION  XLI. 

IRIDIUM. 

Atom.  Num.  98  6— Symb.  Ir.  Sp.  gr.  18-68. 

This  metal  was  discovered  by  Mr.  Tennant  at  the  same  time  with 
the  last.  It  is  the  most  infusible  metal  known,  having  only  been 
fused  by  the  large  galvanic  battery  of  Mr.  Children  ;  when  it  appear- 
ed as  a  globule  of  a  brilliant  white  colour,  and  metallic  lustre  ;  is  at- 
tacked with  great  difficulty  by  nitro-muriatic  acid,  but  is  oxidized  when 
heated  with  nitre. 

Oxides. — The  solution  of  the  oxides  of  iridium  in  muriatic  acid  is, 
when  first  prepared,  of  a  blue  colour  ;  it  afterwards  becomes  of  an  olive 
green,  and  subsequently  acquires  a  deep  red  tint.  These  changes  are 
attributed  to  its  passing  through  different  stages  of  oxidation. 

Berzelius  has  lately  ascertained  that  this  metal  is  capable  of  forming 
four  oxides  and  four  chlorides. 


IRIDIUM.  361 

The  Muriate  of  Iridium,  when  deprived  of  its  excess  of  acid,  by 
heat,  may  be  obtained  in  crystals  of  a  deep  brown  colour,  by  evapo- 
ration. This  salt,  when  dissolved  in  water,  forms'a  red  coloured  so- 
lution, which  is  rendered  colourless  by  pure  alkalies  or  alkaline  earths, 
by  sulphuretted  hjdrogen,  infusion  of  galls,  or  by  ferrocyanate  of  po- 
tassa.  It  is  decomposed  by  nearly  all  the  metals,  except  gold  and 
platinum,  the  iridium  being  thrown  down  in  a  metallic  state.  Iridi- 
um  may  also  be  obtained  from  the  muriate,  by  exposing  that  sail  to  a 
red  heat. 

REFERENCES.  On  the  two  last  Metals,  see  Tennant,  in  Phil.  Trans,  for 
1804.  Vauqueliri's  Memoir  on  Iridium  and  Osmium,  Ann.  de  Chim.  Ixxxix. 
J50,  or  Ann.  of  Phil,  vi,  433.  Wollaston,  Phil.  Trans.  1829.  Berzelius. 
Traite  de  Chim.  iii.  24. 


362  VEGETABLE  SUBSTANCES. 


CHAPTER  IX. 


VEGETABLE  SUBSTANCES. 

All  bodies  which  are  of  vegetable  origin  are  termed  vegetable  sub- 
stances. Oxygen,  hydrogen  and  carbon  are  their  principal  ingredi- 
ents, with  which  a  certain  portion  of  nitrogen  is  sometimes  united ; 
and  variations  in  the  proportions  and  mode  of  combination  of  these 
elements,  occasion  the  great  diversity  which  exists  among  the  pro- 
ducts of  the  vegetable  kingdom. 

Every  distinct  compound  which  exists  ready  formed  in  plants,  is 
called  a  proximate  or  immediate  principle.  Thus  sugar,  starch  and 
gum  are  proximate  principles.  Opium,  though  obtained  from  a  plant, 
is  not  a  proximate  principle,  but  consists  of  several  proximate  princi- 
ples, mixed  more  or  less  intimately  with  one  another.  The  proximate 
analysis  of  vegetables  consists  in  the  separation  of  these  distinct  prin- 
ciples ;  but  the  reduction  of  the  proximate  principles  into  their  simp- 
lest parts,  constitutes  their  ultimate  analysis 

The  proximate  analysis  of  vegetables  varies  considerably  with  the 
nature  of  the  substance  to  be  separated  ;  and  some  of  these  processes 
will  be  hereafter  noticed.  The  ultimate  analysis  consists  in  the  de- 
composition of  the  body  by  heat,  in  contact  with  some  other  sub- 
stance, but  it  constitutes  in  its  details  one  of  the  most  delicate  opera- 
tions of  analytical  chemistry.  For  the  purpose  of  effecting  this  ob- 
ject several  processes  have  been  devised.  That  which  is  at  present 
most  highly  approved  was  proposed  by  Gay  Lussac  and  Thenard, 
and  consists  in  mixing  three  or  four  grains  of  the  substance  to  be  ana- 
lyzed with  about  two  hundred  grains  of  the  peroxide  of  copper,  heat- 
ing the  mixture  to  redness  in  a  glass  tube,  and  collecting  the  gaseous 
products  in  a  graduated  gljss  jar,  over  mercury. — For  the  details  of 
this  process,  and  the  manipulations  necessary,  the  reader  is  referred  to 
the  works  of  T-'teiiard,  Thomson,  Henry  or  fierzelius.  See  also,  Gay 
Lussac  and  Thenard1  s  Physico-Chem.  Kesea.rches,  ii.;  Front's  observa- 
tion? on  tfie  analysis  of  Organic  Substances,  sinn.  of  Phil,  vi  269,  vii. 
Ill  ;  and  his  memoirs  on  the  ultimate  composition  of  Simple  Alimentary 
Substances,  #c.,  Phil.  Trans,  for  1827,  or  Phil.  Mag.  and  Ann.  iii.  31 
and  98. 

Vegetable  substances,  and  indeed  all  organic  products,  are  charac- 
terized as  follows  : 

1.  They  are  composed  of  the  same  elements. 

2.  They  are  easily  decomposed,  both  spontaneously  and  by  art. 

3.  They  cannot  be  formed  by  the  direct  union  of  their  principles. 

4.  They  are   decomposed   at  a    red   heat,    and   often   below   it. — 
burner. 

In  the  present  state  of  our  knowledge,  vegetable  bodies  cannot  be 
classified  in  a  purely  scientific  manner.  I  shall  notice  them  nearly  in 


VEGETABLE    SUBSTANCES.  363 

the  order  proposed  by  Dr.  Turner,  on  the  basis  of  the  general  laws  de- 
duced by  Gay  Lussac  and  Thenard,  viz  : 

1.  Salifying  principles  or  acidr. 

2.  Salifiable  principles   or  alkalies,   and  the   substances  related  to 
them. 

3.  Substances  which,  in  relation  to  oxygen,  contain  an  excess  of  hy- 
drogen. 

4.  Substances,  the  oxygen  and  hydrogen  of  which  are  in  exact  pro- 
portions for  forming  water. 

5.  Substances  which,  so  far  as  is  known,  do  not  belong  to  either  of 
the  preceding  sections. 

SECTION  I. 

VEGETABLE    SALIFYING    PRINCIPLES    OR    ACIDS. 

These  substances  are  characterized  by  their  having  a  sour  taste, 
and  changing  the  blue  of  litmus  to  red,  but  more  especially  by  their 
power  oi  combining  with  salifiable  bases.  Like  all  organic  principles, 
they  are  decomposed  by  a  red  heat ;  though  they  are  in  general  less 
liable  to  spontaneous  decomposition  than  other  vegetable  substances. 
They  are  all  colourless,  and,  with  a  single  exception,  solid ;  and  are 
nearly  all  decomposed  by  hot  nitric  acid,  by  which  they  are  converted 
into  carbonic  acid  and  water. 

Some  of  the  vegetable  acids  are  the  products  of  nature  alone ; 
some  are  the  products  of  both  nature  and  art;  and  some  are  exclu- 
sively the  products  of  art.  I  shall  present  the  prominent  characters 
of  most  of  these  acids,  noticing  in  detail  only  the  most  important. 

Acetic  Acid.— Atom.  Num.  5l—Symb.  3O+3H+4C. 

NATIVE  STATE  AND  PROPERTIES.  This  acid  exists  in  the  sap  of  al- 
most all  plants,  either  free  or  combined  with  potassa  or  lime,  and 
is  also  abundantly  the  produce  ot  art.  It  is  transparent,  colour- 
less, and  very  volatile  ;  has  a  pungent  odour,  very  sour  taste,  and  red- 
dens litmus  powerfully;  in  its  most  concentrated  form  it  crystallizes 
when  exposed  to  a  low  temperature,  retaining  its  solidity  until  the 
thermometer  rises  to  50°  F.  It  has  a  specific  gravity  varying  from 
I -056  to  1-08. 

PREPARATION.  Acetic  acid  may  be  obtained  by  the  distillation  of 
common  vinegar,  which  is  prepared  by  exposing  malt  or  vinous 
liquors  to  the  free  access  of  atmospheric  acid,  at  a  temperature  slight- 
ly elevated  ;  by  the  purification  of  pyroligneous  acid  procured  from  the 
distillation  of  wood  ;  or  still  better,  by  the  decomposition  of  the 
acetates. 

The  distillation  of  vinegar  is  effected  in  the  same  manner  as  that  of 
water.  The  acid  thus  obtained  is  called  Distilled  Vinegar,  and  was 
formerly  named  Acetous  Acid,  upon  the  erroneous  supposition  that  it 
was  chemically  different  from  strong  acetic  acid. 

Concentrated  acetic  acid  is  best  prepared  by  the  decomposition  of 
the  acetate  of  soda  by  sulphuric  acid,  and  subsequent  distillation  ;  or 
by  subjecting  the  acetate  of  copper  to  heat.  The  acid,  when  first 


364         VEGETABLE  SUBSTANCES. 

collected,  has  a  greenish  tint,  owing  to  the  presence  of  copper,  from 
which  it  is  freed  by  a  second  distillation. 

In  addition  to  the  above  processes  may  be  mentioned,  the  exposure 
of  common  vinegar  to  low  degrees  of  temperature,  by  means  of 
which  the  water  is  frozen,  and  a  concentrated  acid  remains  in  a  liquid 
state. 

Pyroligneous  Acid. — The  acid  known  under  this  name  is  an  impure 
acetic  acid  prepared  by  the  distillation  of  wood.  When  first  made,  it  it 
of  a  dark  colour,  holding  in  solution  tar  and  volatile  oil,  from  which  it  is 
freed  by  mixing  it  with  chalk,  decomposing  the  resulting  acetate  of  lime 
by  digestion  with  sulphate  of  soda  ;  fusing  the  acetate  of  soda  thus 
formed  at  a  high  temperature,  insufficient  to  decompose  the  salt,  but 
sufficient  to  expel  or  char  the  impurities  ;  and  finally  decomposing  the 
acetate  of  soda  by  sulphuric  acid. 

Kreosote. 

Mr.  Reichenbach  has  recently  obtained  from  pyroligneous  acid  and 
also  from  the  tarry  matter  which  distils  over  with  the  acid,  a  new  sub- 
stance which  he  calls  Kreosole,  from  the  greek  words  meaning  flesh,  I 
save.  This  substance  is  highly  interesting,  not  only  on  account  of  its 
chemical  properties,  but  from  its  useful  applications  to  therapeutics. 
domestic  economy  and  the  preservation  of  provisions  for  long  voyages, 

Kreosote  is  an  oily,  colourless  liquid,  possessing  great  refrangibility  , 
has  a  penetrating,  disagreeable  odour,  similar  to  that  of  smoked  beef; 
sp.  gr.  about  1-037  at  68°  F.,  boils  at  397°  F.,  and  is  not  congealed  at 
a  temperature  of  16'6°  F  ;  burns  with  a  smoky  flame  ;  combines  readi- 
ly with  acetic  acid,  Water,  alcohol,  ether  and  with  the  alkalies  ;  it  also 
coagulates  albumen. 

Antiseptic  properties  of  Kreosote. — When  fresh  meat  is  put  into  a  so- 
lution of  kreosote,  allowed  to  remain  for  half  an  hour  or  an  hour, 
withdrawn,  and  afterwards  dried,  it  may  be  exposed  to  the  heat  of  the 
sun  without  putrifying,  and  in  the  space  of  eight  days  it  becomes  hard, 
the  colour  changes  to  a  reddish-brown,  and  the  flavour  is  that  of  good 
smoked  beef.  Fish  may  also  be  preserved  by  it, 

Action  on  the  Animal  Economy. — When  kreosote  is  placed  upon  the 
tongue,  it  occasions  violent  pain,  and  when  poured  in  a  concentrated 
state  upon  the  skin  it  destroys  the  epidermis.  Insects  and  fish  thrown 
into  it,  immediately  die.  Jt  has  been  employed  with  success  in  cases 
of  caries,  of  cancer  and  of  carcinomatous  ulcers. — Land,  and  Edin. 
Phil.  Mag.  iv.  391.  Edin.  Med.  and  Surg.  Jour.  xli.  248. 

REFERENCES.  CrelUs  Annals.  Aikirfs  Did.  art.  Acetous  Add.  For 
various  processes  for  preparing  this  add,  see  also  lire's  Chem.  Diet.  4th  ed. 
7.  Thenard's  Traite  de  Chim.  and  Chaptal.  Despretz'  method  of  making 
glacial  acetic  add,  by  heating  a  mixture  of  one  atom  of  acetate  of  Lead,  well 
dried,  with  one  of  concentrated  sulphuric  acid,  Phil.  Mag.  and  Ann.  vii.  317. 
Parked  Essays  on  Pyroligneous  Acid. 

The  only  correct  mode  of  estimating  the  strength  of  acetic  acid,  is 
by  its  neutralizing  power ;  its  specific  gravity  being  no  criterion.  Sec 
a  Table  in  Thomsons  First  Prin.  ii.  135. 

Acetates. — These  are  compounds  formed  by  the  union  of  acetic  acid 


VEGETABLE  SUBSTANCES.  365 

with  bases.  They  are  nearly  all  soluble  in  water,  and  can  be  decom- 
posed by  sulphuric,  muriatic,  nitric,  hydrofluoric  or  phosphoric  acids. 
When  subjected  to  destructive  distillation,  they  furnish,  in  addition 
to  the  usual  products,  a  modified  vinegar,  which  has  been  termed 
Pyroacetic  Acid  or  Spirit. — See  M.  M.  Macaire  and  Marcel's  description 
and  analysis  of  Pyroxilic  and  Pyroacetic  Spirit,  in  Ann.  of  Phil.  xxiv. 
69. 

Ace  fate  of  Ammonia. — Atom.  Num.  131 — Symb.  (3H-fN)+ 
Ac*+7  Aq. 

Crystallizes  with  difficulty,  being  deliquescent  and  very  soluble  in 
water  and  in  alcohol ;  has  a  hot  and  aromatic  taste.  It  may  be  ob- 
tained in  solution  by  saturating  distilled  vinegar  with  carbonate  of  am- 
monia, and  it  then  constitutes  the  Spirit  of  Mindtrerus,  long  used  in 
medicine  as  a  febrifuge. 

Acetate  of  Potassa. — Atom.  Num.  116.15 — Synib.   (O-fPo.) 
+Ac+2  Aq. 

Formerly  known  by  the  name  of  Terra  Foliata  Tartari,  Febrifuge 
Salt  of  Sylvius,  and  Diuretic  Saft.  This  salt,  when  cautiously  evapo- 
rated, forms  irregular  crystals,  which  are  with  difficulty  obtained,  ow- 
ing to  their  deliquescence.  It  exists,  according  to  Vauquelin,  in  small 
quantity,  in  the  sap  of  almost  all  plants,  and  is  formed  artificially  by 
neutralizing  carbonate  of  potassa  with  acetic  acid,  or  by  decomposing 
acetate  of  lime  with  sulphate  of  potassa. 

Acetate  of  Soda.— Atom.  Num.  138-3— Symb.  (O+So)+Ac. 
+6Aq. 

Formerly  known  by  the  name  of  Terra  Foliata  Crystallizata.  It 
crystallizes  in  long  striated  prisms  ;  has  an  acrid  and  bitter  taste  ;  is 
soluble  in  a  third  of  its  weight  of  water,  at  60°  F.  It  is  prepared  by 
saturating  acetic  acid  with  carbonate  of  soda,  and  evaporating  the  so- 
lution. When  it  is  employed  in  the  manufacture  of  acetic  acid,  it  is 
prepared  by  the  decomposition  of  sulphate  of  soda  by  acetate  of  lime 
made  with  pyroligneous  acid. 

Acetate  of  Baryta  is  sometimes  employed  as  a  re-agent,  and  Acetate 
of  Alumina  is  used  by  dyers  and  calico  printers  as  a  basis  or  mor- 
daunt. 

Acetates  of  Copper. 

These  salts  have  been  carefully  investigaged  by  Berzelius  and  Phil- 
lips.— Ann.  of  Phil.  xvii.  217.  xviii.  21.  xx.  161.  xxiv.  192.  xxviii.  188. 

Acetate  of  Copper. — The  neutral  acetate  may  be  formed  either  by 
dissolving  oxide  of  copper  or  common  verdigris  in  acetic  acid  or  by  de- 

*  Ac  is  used  as  an  abbreviation  for  the  acid  of  a  salt  when  the  symbol  is 
complex.  Aq.  as  heretofore,  is  an  abbreviation  for  aqua,  water. 

X 


366  VEGETABLE    SUBSTAN7CES. 

composing  sulphate  of  copper  by  acetate  of  lead.  Ft  crystallizes  in 
oblique  rhombic  prisms,  of  a  beautiful  bluish-green  colour,  which  are 
soluble  in  20  times  their  weight  of  cold  water,  in  5  of  boiling  water, 
and  in  14  of  boiling  alcohol.  They  consist  of  1  atom  acetic  acid,  1 
atom  of  the  black  oxide  of  copper  and  1  of  water=99. 

Diacetate  of  Copper.  —  This  constitutes  the  chief  ingredient  of  the 
pigment  called  Verdigris,  which  is  prepared  in  the  large  way  by  cover- 
ing copperplates  with  cloth  soaked  in  pyroligneous  acid,  or  by  cover- 
ing copper  plates  with  the  refuse  of  the  g'  ape  after  the  juice  has  been 
extracted  for  making  wines,  as  is  practiced  in  the  south  of  France.  — 
The  saccharine  matter  contained  in  the  husk  furnishes  acetic  acid  by 
fermentation,  and  in  four  or  six  weeks  the  plates  acquire  a  coating  of 
this  salt.  It  consists  of  1  atom  acetic  acid,  2  atoms  black  oxide  of 
eopper,  and  6  atoms  of  water=144. 

This  salt  is  decomposed  by  water  and  converted  into  a  soluble  green 
sesquiacctate  and  an  insoluble  tri-acetate.  —  See  the  papers  above  referred  to 
and  Thomson's  First  Prin.  ii.  383,  and  Inorg.  Chem.  ii.  672. 

Acetate  of  Lead.  —Atom.  Num.  lSQ'5—Symb.  (O-f  Pb)+Ac. 
+3  Aq. 

Known   also  by   the   names  of  Raccharum  Saturni  and    Sugar  of 


This  salt,  when  pure,  crystallizes  in  long  six-sided  prismatic  crys- 
tals ;  it  has  a  taste  at  first  sweet,  then  astringent  ;  has  no  effect  upon 
vegetable  blues,  being  perfectly  neutral  ;  is  very  soluble  in  water  ; 
effloresces  when  exposed  to  the  air,  and  is  partially  converted  into  a 
carbonate.  It  is  prepared  by  dissolving  either  carbonate  of  lead  or  li- 
tharge in  distilled  vinegar.  It  is  used  in  medicine  as  an  external  ap- 
plication, &c.  ;  in  the  arts,  in  the  preparation  of  acetate  of  alurnine  ; 
and  in  the  laboratory  as  a  re-agent. 

Subacctate  of  Lead.  —  Jjtom.  Num  335*5  —  Symb. 
3(O+Pb)+Ac. 

This  compound,  commonly  known  by  the,  name  of  Extractum  Satur- 
m,  or  Goulard's  Extract  of  Lead,  is  prepared  by  boiling  one  part  of  neu- 
tral acetate,  and  two  parts  of  litharge,  deprived  of  carbonic  acid  by 
heat,  with  25  parts  of  water.  It  crystallizes  in  white  and  opaque 
plates  ;  has  a  taste  less  sweet,  and  is  less  soluble  in  water,  than  the 
neutral  acetate,  and  changes  to  green  the  syrup  of  violets.  It  has  a 
strong  attraction  for  vegetable  colouring  matter,  and  upon  this  princi- 
ple was  employed  by  Mr.  Brande  in  his  analysis  of  wines.  —  Phil.  Trans. 
1813. 

This  salt  is  called  by  Dr.  Thomson  the  Trisacctatc,  and  he  has  also 
described  a  Diacetate,  formed  by  boiling  with  water  a  mixture  of  li- 
tharge and  acetate  of  lead,  in  atomic  proportions.  —  First  Prin.  ii.  373, 
and  Inorg.  Chem.  ii.  642. 

Oxalic  Acid.—  Atom.  Num.  36—Symb.  3O+2C. 

STATE  AND  PROPERTIES.  Discovered  by  Scheele,  and  exists  in  the 
juice  of  several  plants,  especially  in  that  of  the  Rumex  Acetosa,  L.  or 
common  sorrel,  and  in  the  Oxaiis  Aceiosdla  L.  or  wood  sorrel  ;  but 


VEGETABLE  SUBSTANCES.          367 

it  almost  always  occurs  in  combination  either  with  lime  or  potassa. — 
It  may  also  be  prepared  artificially  by  the  action  of  nitric  acid  upon 
various  vegetable  and  animal  substances.  It  crystallizes  in  slender, 
flattened  four  or  six-sided  prisms,  with  two-sided  summits,  the  prima- 
ry form  of  which  is  an  oblique  rhombic  prism  ;  it  has  a  very  acrid 
taste,  and  reddens  litmus  strongly  ;  is  soluble  in  two  parts  of  water  at 
(50°  and  in  its  own  weight  at  2l5°  and  also  in  boiling  alcohol ;  eilior- 
esces  when  exposed  to  the  air,  and  at  a  red  heat  is  decomposed.  It 
differs,  in  composition,  from  all  the  other  vegetable  acids,  in  contain- 
ing no  hydrogen.  —  Berzdius,  Ann.  dc  Chim.  ct  de  Phys.  xviii.  155. 
Thomson's  First  Prin.  ii.  100.  See  also  Dobcreiner,  in  dnn.  de  Chim.  et 
de  Pliys.  xix. 

Oxalic  acid  may  be  easily  made  artificially,  by  digesting  sugar  in 
iive  or  six  times  its  weight  of  nitric  acid,  and  expelling  the  excess  of 
that  acid  by  distillation,  until  a  fluid  of  the  consistence  of  syrup  re- 
mains in  the  retort.  The  residue,  in  cooling,  yields  crystals  of  oxalic 
acid,  the  weight  of  which  amounts  to  rather  more  than  half  the  quan- 
tity of  the  sugar  employed.  These  crystals  are  to  be  re-dissolved  in 
water,  and  again  crystallized,  by  which  the  pure  acid  is  obtained. 

Other  processes  have  been  proposed  by  Braconnot  for  obtaining  this 
acid  from  lichens. — .inn.  de  Chim.  xxviii.  313. 

ACTION  ON  THE  ANIMAL  ECONOMY.  Oxalic  ackl  is  one  of  the  most 
powerful  and  rapidly  fatal  poisons  that  we  possess  ;  and  frequent  ac- 
cidents have  occurred  in  consequence  of  the  resemblance  of  the  crys- 
tals to  those  of  Epsom  salts.  Its  acidity,  however,  will  be  a  sufficient 
mark  of  distinction,  which  can  be  detected  either  by  the  taste  or  by 
its  reddening  blue  papers.  The  solution  also  of  a  small  quantity  of 
this  acid,  when  added  to  chalk,  causfs  effervescence,  which  is  not 
the  case  with  the  salt.  When  the  acid  has  been  swallowed,  copious 
draughts  of  lime-water,  chalk  or  magnesia  and  water,  should  be  ad- 
ministered, and  vomiting  excited  as  speedily  as  possible. — Christison 
and  CGindet,  in  Edin.  Mud.  and  Surg.  Jour.  1823. 

TESTS.  Oxalic  acid  is  distinguished  from  all  other  acids  by  the  form 
of  its  crystals,  and  by  its  forming,  with  lime-water,  an  insoluble  pre- 
cipitate. It  is  hence  employed  as  a  test  for  lime  ;  but  for  this  purpose 
the  combination  of  oxalic  acid  with  ammonia  is  generally  preferred. 

Oxidates.  These  compounds  are  either  insoluble  or  sparingly  solu- 
ble in  water,  but  they  are  all  dissolved  by  the  nitric,  and  also  by  mu- 
riatic acid,  except  when  the  latter  precipitates  the  bases  of  the  salts. 
The  only  oxalates  remarkable  for  solubility  are  those  of  potassa,  soda, 
lithia,  ammonia,  alumina  arid  iron. 

These  salts  are  decomposed  at  a  red  heat  r  but  they  are  with  diffi- 
culty acted  upon  by  the  acids.  They'are  formed  either  directly  or  by 
double  decomposition. 

Oxalatc  of  Ammonia.— A  tow.  Num.  71—Symb.   (3H+N) 
+ Ac+2  Aq. 

This  salt  crystallizes  in  long  tetrahedrons,  terminated  by  two-sided 
summits  ;  it  has  a  very  pungent  taste  ;  is  soluble  in  two  parts  of  wa- 
ter, at  6(P  F.  insoluble  in  alcohol.  It  is  prepared  by  the  direct  union 
of  its  constituents,  and  is  employed  in  the  laboratory  as  a  test  for 
lime. 

During  the  decomposition  of  this  salt  by  heat,  a  sublimate  of  a  pe- 


368          VEGETABLE  SUBSTANCES. 

culiar  nature  is  formed,  which  is  named  by  Dumas,  its  discoverer, 
Oxalammide  or  Oxamide,  compounded  of  the  words  oxalic  and  ammonia.'. 
It  is  of  a  dirty  white  colour,  insoluble  in  cold  water,  but  is  dissolved  in 
boiling  water,  from  which  on  cooling  it  is  deposited,  unchanged,  in 
the  form  of  whitish  fiocks  of  a  confused  crystalline  appearance. — 
when  gently  heated  in  an  open  tube  it  rises  in  vapour,  and  is  again 
condensed  on  the  cold  part  of  the  tube  ;  but  when  sharply  heated,  it 
enters  into  fusion,  and  while  part  sublimes,  another  portion  yields 
cyanogen  gas,  and  leaves  a  very  bulky  carbonaceous  residue.  It  con- 
sists, according  to  Dumas,  of  2  atoms  carbon,  1  atom  nitrogen.  2 
atoms  hydrogen  and  1  atom  oxygen=36. — Ann.  de  Chim.  et  de  Pliys* 
xliv.  12&—Berzelius,  Traite  de  Chim. 

Binoxolate  of  Ammonia.— Atom.  Num.  161 — Symb.  (3H+N^ 
+2Ac+8  Aq. 

This  salt  may  be  formed  by  adding  oxalic,  sulphuric,  nitric  or  muri- 
atic acid  to  a  solution  of  oxalate  of  ammonia  and  setting  the  solution 
aside  (sufficiently  concentrated)  for  crystallization. 

Oxalate  of  Potassa.—Atom.  Num.  92*15— Symb.  (Q+Po) 
+Ac+Aq. 

A  neutral  salt,  which  crystallizes  with  some  difficulty  in  flat,  ob- 
lique, four-sided  prisms,  terminated  by  diedrai  summits  ;  it  is  soluble 
in  about  twice  its  weight  of  water,  at  60°  F. ;  has  a  cooling  and  bitter 
taste.  It  is  prepared  by  neutralizing  oxalic  acid  with  carbonate  of 
potassa. 

Binoxolateof  Potassa.— Atom.  Num.  137.15—  Symb.  (O-f-Po) 
+ 2Ac+2  Aq. 

This  salt  crystallizes  in  rhombs,  only  slightly  oblique  ;  it  has  a  sour . 
pungent  bitterish  taste,  and  reddens  vegetable  blues  ;  is  soluble  in  ten 
times  its  weight  of  boiling  water.  It  exists  ready  formed,  in  the  sorrel 
and  other  plants,  from  which  it  may  be  obtained  by  solution  and  crys- 
tallization. Artificially  it  may  be  obtained  by  adding  oxalic  acid  to  a 
concentrated  solution  of  the  natural  oxalate.  It  is  commonly  known 
by  the  names  of  Salt  of  Sorrel  or  Essential  Salt  of  Lemons,  and  is  used 
for  the  removal  of  ink  stains  from  linen,  &c. 

Quadroxalate  of  Potassa. — Atom.  Num.  254' 15 — Symb. 

(O+Po)+4Ac-f 7  Aq. 

A  salt  crystallizing  in  octahedrons,  reddening  litmus  powerfully 
and  less  soluble  in  water  than  the  preceding.  It  is  obtained  by  di- 
gesting the  binoxalate  in  nitric  or  muriatic  acid.  —  On  these  Oxalatc? 
consult  Wollaston  on  Super-acid  and  Sub-add  Salts,  in  Phil.  Trans,  for 
1808,  and  Berard,  in  Ann.  de  Chim.  Ixxiii.  271.  An  Oxalate  and  Bi 
noxalate  of  Soda  arc  also  described  by  Dr.  Thomson,  First  Prin.  ii, 


VEGETABLE     SUBSTANCES.  369 

Oxalote  ofLimt — Atom.  Num.  82*5— Symb.  (O-f  Ca)+ 
Ac+2  Aq. 

A  white  tasteless  powder,  insoluble  in  water,  but  soluble  in  nitric 
and  muriatic  acid  ;  when  heated  to  560°  F.  it  becomes  anhydrous.  It 
is  a  frequent  ingredient  of  urinary  concretions,  and  is  the  basis  of 
what  is  called  the  Mulben-y  Calculus.  Artificially  it  is  prepared  by  ad- 
ding any  soluble  oxalate  to  a  salt  of  lime. 

Qxalate  of  Magnesia. — Atom.   Num.  70-7 — Symb.  (O+Mg) 
-fAc+Aq. 

A  white,  tasteless  powder,  which  is  sparingly  soluble  in  water.  It 
'is  prepared  by  adding  oxalate  of  ammonia  to  a  hot  concentrated  solu- 
tion of  sulphate  of  magnesia.  When  the  sulphate  of  magnesia  is  mod- 
erately diluted  with  cold  water  no  precipitate  is  occasioned  by  the  ad- 
dition of  the  oxalate.  On  this  fact  is  founded  one  of  the  best  process- 
es for  separating  lime  from  magnesia. 

Tartaric  Acid— Atom.  Num.  ffi—Symb.  5O+2H-f-4C. 

STATE  AND  PROPERTIES.  Thi-s  acid  was  discovered  by  Scheele  in 
1770,  and  exists  in  combination  with  lime  and  potassa  in  the  juice  of 
several  acidulous  fruits.  It  occurs  in  prismatic  crystals,  the  primary 
form  of  which  is  a  right  rhombic  prism  ;  has  a  very  sour  taste,  and 
reddens  litmus  powerfully  :  is  soluble  in  five  or  six  times  its  weight  of 
water  at  60°  F. ;  when  exposed  to  heat  it  melts,  is  decomposed,  and 
yields,  in  addition  to  the  usual  products  of  destructive  distillation,  a 
distinct  acid,  to  which  the  name  of  Pyrotartaric  Acid  is  applied  ;  it  un- 
dergoes no  change  by  exposure  to  air,  but  its  aqueous  solution  soon  be- 
comes covered  with  mould. 

Tartaric  acid  is  prepared  by  throwing  into  boiling  water  a  mixture 
of  197-15  parts  or  one  proportion  of  cream  of  tartar,  with  50*5  parts  or 
one  proportion  of  chalk,  decomposing  the  tartrate  of  lime  which  re- 
sults, with  one  proportion  of  sulphuric  acid,  filtering  and  evaporating 
the  solution. 

This  acid  combines  with  bases  and  forms  salts,  called  Tartrates,  and 
it  is  distinguished  by  its  forming  a  white  precipitate,  the  bitartrate  of 
potassa,  when  mixed  with  any  salt  of  that  alkali.  Its  great  use  is  by 
the  calico-printers,  who  thicken  it  with  gum  or  roasted  starch,  and 
apply  it  to  those  parts  of  a  piece  of  calico  previously  dyed  red  or  blue 
as  are  to  be  rendered  colourless  by  means  of  chloride  of  lime.  The 
tartaric  acid  combining  with  the  lime  sets  the  chlorine  at  liberty, 
which  immediately  destroys  the  colour  of  the  part  of  the  cloth  on 
which  the  thickened  acid  has  been  fixed. 

Tartrate  of  Potassa.— Atom.  Num.  13M5— Symb.  (O-fPo) 
+Ac-f2  Aq. 

This  salt,  frequently  called  Soluble  Tartar,  occurs  in  crystals,  the 
primary  form  of  which  is  a  right  rhomboidal  prism,  and  which  are  so- 
luble in  water,  and  attract  moisture  when  exposed  to  the  air.  It  is 


370  VEGETABLE  SUBSTANCES. 

formed  by  neutralizing  a  solution  of  the  bitartrate  with  carbonate  of 
potassa. — For  an  account  of  the  forms  of  its  crystals ,  see  Brooke,  in  .^nn  . 
of  Phil.  vii.  161. 

Bitartrate  of  Poiassa. — Atom.  Num.  197*15 — Symb. 
(O+Po)+2  Ac+2  Aq. 

Also  called  Supcr-tartrate  of  Potassa,  Cream  of  Tartar,  and  in  an 
impure  form,  Tartar.  This  salt  is  very  sparingly  soluble  in  wafer,  re- 
quiring sixty  parts  of  cold  and  fourteen  of  boiling  water  for  solution., 
from  the  latter  of  which  it  is  deposited  in  small  crystalline  grains,  the 
primary  form  of  which  is  either  a  right  rectangular,  or  a  right  rhom- 
bic prism  ;  it  has  a  sour  taste,  and  reddens  vegetable  blues.  It  exist* 
in  the  juice  of  the  grape,  and  owing  to  its  insolubility,  is  deposited  on 
the  sides  and  bottom  of  wine  casks  ;  from  which  source  all  the  tartar 
of  commerce  is  obtained,  and  which,  by  being  purified,  furnishes  the 
cream  of  tartar  of  the  shops.  It  is  used  in  forming  the  black  and 
white  flux,  and  in  the  preparation  of  tartaric  acid  and  the  tartrates. — 
For  the  crystalline  form  of  this  Salt,  see  Ann. 'of  Phil.  x.  37,  and  xxiii. 
161.  The  processes  commonly  adopted  in  manufacturing  tJtis  Salt,  arz 
described  in  Mkins  Chem.  Diet.  ii.  art.  Tartar. 

Tartrate  of  Potassa  and  Soda. — Atom.  Num.  282-45. 

This  double  salt,  which  has  long  been  used  in  medicine  under  the 
name  of  Rochdle  Salt,  occurs  in  prismatic  crystals,  having  often  ten 
or  twelve  sides,  the  primary  form  of  which  is  a  right  rhombic  prism  : 
it  is  soluble  in  five  parts  of  cold  water,  and  in  a  less  quantity  of  boiling 
water.  It  is  obtained  by  neutralizing  bitartrate  of  potassa  with  car- 
bonate of  soda. 

Boro-tartrate  of  Potassa  and  Soda. — A  salt  made  by  dissolving  one 
part  of  borax  in  eight  parts  of  boiling  water,  and  adding  three  parts  of 
tartar,  or  as  much  as  it  is  capable  of  dissolving.  It  has  a  place  in  most 
of  the  German  Pharmacopoeias  under  the  name  Cremor  Tartari  Soht- 
Iiilis  and  Tartras  Potassce  Boraxatvs.  It  is  said  to  possess  nearly  the 
same  properties  as  cream  of  tartar. — Thomson's  Inorg.  Chem.  ii.  805. 

Tartrate  of  Antimony  and  Potassa — Tartar  Emetic. — Atom, 
Num.  350-35. 

PROPERTIES.  This  salt  commonly  crystallizes  in  tetrahedrons, 
which  are  transparent  when  first  formed,  but  become  white  and  opake 
by  exposure  to  the  air.  It  has  a  styptic  metallic  taste  ;  reddens  litmus 
slightly  ;  is  soluble  in  fifteen  parts  of  water  at  60°  F.  and  in  three  of 
boiling  water  ;  its  aqueous  solution  undergoes  spontaneous  decompo- 
sition by  keeping. 

PREPARATION.  Tartar  emetic  is  obtained  by  boiling  protoxide  of  an- 
timony with  a  solution  of  bitartrate  of  potassa.  For  this  purpose, 
the  oxide  is  variously  prepared.  The  method  recommended  by  Mr. 
Phillips  is  to  boil  100  parts  of  metallic  antimony  in  fine  powder  to 
dryness,  in  an  iron  vessel,  with  *200  parts  of  sulphuric  acid  ;  and  to 
boil  the  residual  subsulphate  with  an  equal  weight  of  cream  of  tartar. 
The  solution  is  then  concentrated  by  evaporation,  and  allowed  to 


VEGETABLE   SUBSTANCES.  371 

cool  in  order  that  crystals  may  form.  According  to  Dr.  Thomson,  this 
salt  consists  of  two  atoms  tarlaric  acid,  three  protoxide  of  antimony, 
one  atom  potassa  and  two  atoms  water,  =354. — First  Prin.  ii.  441. 
For  a  copious  abstract  of  an  elaborate  memoir  on  Tartar  Emetic,  by  M. 
Henrv,  of  Paris,  see  the  Supplement  to  Duncan's  Edin.  New  Dispensa- 
tory, (1829.) 

ACTION  ON  THE  ANIMAL  ECONOMY.  Most  commonly  tartar  emetic 
is  evacuated  by  vomiting,  before  it  can  produce  any  striking  consti- 
tutional effect.  But  in  cases  of  poisoning  when  large  does  have  been 
exhibited,  and  it  remains  long  on  the  stomach,  burning  pain  in  the 
stomach  comes  on,  with  purging,  colic  pains,  violent  and  long  contin- 
ued vomiting  ;  cramp  is  also  common.  The  resemblance  of  these 
symptoms  to  cholera  morbus  will  strike  the  physician. 

TESTS.  1.  Sulphuretted  hydrogen  gives  an  orange-red  precipitate. 
— the  Sulphuret  of  Antimony.  2  Carbonate  of  potash  throws  down  a 
white  precipitate.  3.  The  sulphuret  obtained  as  above,  after  being- 
dried,  is  placed  in  a  small  glass  vessel,  a  stream  of  hydrogen  is  then 
passed  on  it  from  a  proper  apparatus, — heat  is  afterwards  applied  by 
a  spirit  lamp,  and  on  producing  an  elevated  temperature,  metallic  an- 
timony is  seen,  either  in  minute  globules,  or  in  a  spongy  mass.  This 
experiment,  for  which  we  are  indebted  to  Professor  Turner,  depends 
on  the  property  that  hydrogen  possesses  of  separating  sulphur  from 
antimony. 

REFERENCES.  Dr.  Turner,  in  Edin.  Med.  and  Snrg.  Journal,  xxviii. — 
Christisoii,  on  Poisons. 

Tartrate,  of  Copper  and  Potassa. — This  salt  may  be  formed  bj 
boiling  together  oxide  of  copper  and  tartar  in  water.  The  solution 
yields  by  evaporation  blue  crystals,  which  have  a  sweetish  taste,  and 
contain  a  great  proportion  of  metal.  When  tartar  and  copper,  or  its 
oxides,  are  boiled  together,  they  dissolve,  and  by  evaporating  to  dryness, 
a  bluish-green  powder  is  obtained,  which,  according  to  Leonardi,  con- 
stitutes the  better  kind  of  pigment,  called  Brunswick- green. — Thomsons 
Inorg.  Chem.  ii.  798. 

Racemic  or  Paratartaric  Add. 

Shown  to  be  a  distinct  acid  by  John,  in  1819,  a  view  which  was  con- 
firmed by  Gay  Lussac  and  Walckner  in  1829. 

PROPERTIES.  This  acid  occurs  in  the  form  of  prisms  and  of  large 
oblique  rhombs  which  are  perfectly  diaphanous  ;  is  very  sour,  but  with- 
out odour  ;  melts  easily  and  becomes  yellow  when  heated. 

It  possesses  exactly  the  same  composition  and  power  of  saturation 
as  tartaric  acid  ; — in  consequence  of  which  Berzelius  suggested  the 
name  of  Paratartaric  Acid. 

PREPARATION.  This  acid  may  be  prepared  by  saturating  the  tartar 
of  sour  wine  with  carbonate  of  soda,  and  crystallizing  the  double  tar- 
trate.  The  double  paratartrate  does  not  crystallize,  and  remains  in  the 
mother  water.  It  is  then  decolourized  as  much  as  possible  by  animal 
charcoal  and  precipitated  by  a  salt  of  lime  or  of  lead — the  precipitate, 
if  a  salt  of  lime,  is  decomposed  by  sulphuric  acid — if  of  lead,  by  sul- 
phuretted hydrogen.  The  solution  then  contains  tartaric  and  paratar- 
taric  acid  ;  the  last  crystallizes  first,  and  the  tartaric  acid  only  assumes 


372          VEGETABLE  SUBSTANCES. 

the  solid  form  when  the  mother  water  becomes  of  the   consistence  of 
syrup. — Berzelius,  Traite  de  Chim.  v.  83. 
Berzelius  describes  several  Paratartratcs. 

Citric  Acid.— Atom.  Num.  5S—Symb.  4O+2H+4C 

STATE  AND  PROPERTIES.  This  acid,  discovered  by  Scheele,  is  found 
in  very  large  quantity  in  the  juice  of  the  lime  and  lemon.  It  crystal- 
lizes, in  large  and  transparent  rhomboidal  prisms,  which  are  termina- 
ted by  four  plane  surfaces,  and  undergo  no  change  in  the  air ;  when 
concentrated  it  has  a  very  sour  and  almost  insupportable  taste,  and 
reddens  litmus  powerfully  ;  is  soluble  in  an  equal  weight  of  cold,  and 
half  its  weight  of  boiling  water ;  when  exposed  to  heat  it  is  decom* 
posed,  and  besides  the  usual  products,  a  peculiar  acid  sublimes,  call* 
ed  Fyrocitric  J)cid.  It  is  obtained  from  lemon  juice,  by  a  process  very 
similar  to  that  for  obtaining  tartaric  acid. 

This  acid  is  sometimes  used  as  a  substitute  for  lemon  juice,  and 
when  added  to  the  carbonates  of  potassa  or  soda,  forms  an  efferves- 
cing draught.  It  combines  with  various  bases,  and  forms  Citrates,  but 
these  are  of  little  importance. 

REFERENCES.  For  a  very  full  account  of  Citric  Acid,  see  Parked  Chtm. 
Essriys,  iii.  3.  Lassaigne,  on  Pyrocitric  Acid,  Ann.  de  Chim.  ft  de  Phys  of 
Repert.  of  Arts,  3d  ser.  xlii.  251. 

Malic  Acid.—Jltom.  Num.  57 — Symb.  4O+H+4C.  lAebig. 

STATE  AND  PROPERTIES.  This  acid,  discovered  by  Scheele  in  1785, 
is  found  inmost  of  the  acidulous  fruits,  as  grapes,  currents,  gooseber* 
ries,  &c.,  and  in  the  Scrnpermvum  tectorwn ,  L.  and  Sorbus  aucvparia,  L. 
and  may  be  formed  by  digesting  sugar  with  three  times  its  weight  of 
nitric  acid.  It  is  white,  inodorous,  and  difficultly  crystallizable  ;  has 
a  sour  taste,  resembling  that  of  the  citric  and  tartaric  acids  ;  is  deli- 
quescent and  soluble  in  water  and  alcohol  ;  has  a  specific  gravity  great- 
er than  that  of  water,  and  by  the  action  of  heat  is  converted  into  a 
distinct  and  volatile  acid,  called  lyromalic  Acid. 

The  compounds  of  this  acid  with  bases,  called  Malates,  are  mostly 
soluble  in  water. 

REFERENCES.  Donovan,  Le  Grange,  Vogel  and  Braconnot,  on  Malic 
Acid, in  Ann.  of  Phil.  vi.  67;  xii.  153;  xiii.  51.  Braconnot  and  Labillar- 
diere's  proofs  of  the  identity  of  the  Sorbic  and  Malic  Acid,  Ann.  de  C/tiui.  et 
de  Phys.  viii.  149  and  214.  Thenard,  Traite  de  Chim.  iii.  622. 

Benzole  Acid.— Atom.  Num.  113— Symb.  3O+5H+14C. 

Flowers  of  Benzoin  of  the  shops. 

STATE  AND  PROPERTIES.  Exists  in  the  Styrax  Berizoin,  Dryand.  And 
in  the  flowers  of  the  Melilotus  officinalis,  Lam.  It  occurs  in  white 
opaque,  prismatic  crystals,  of  a  satin  appearance  ;  has  a  sweetish  and 
aromatic,  rather  than  a  sour  taste,  though  it  reddens  litmus  and  unites 
with  bases  ;  is  soluble  in  about  30  parts  of  boiling  water,  and  very 
sparingly  so  in  cold  water  ;  is  also  soluble  in  alcohol.  It  combines 
with  bases  and  forms  a  class  of  salts,  called  Benzoatcs,  most  of  which 
are  soluble. 


VEGETABLE  SUBSTANCES.          373 

PREPARATION  This  acid  may  be  obtained  by  heating  gum  benzoin 
in  an  earthen  pot,  and  receiving  the  acid  as  it  sublimes  in  a  cone  of 
paper  placed  over  it ;  or  by  boiling  powdered  gum  benzoin  in  a  large 
quantity  of  water,  along  with  carbonate  of  potassa  or  lime,  and  adding 
muriatic  acid  to  the  solution  after  being  filtered  and  evaporated.  But 
perhaps  the  simplest  process  is  to  digest  gum  Benzoin  in  sulphuric 
acid,  when  a  great  quantity  of  beautifully  crystallized  and  very  pure 
benzoic  acid  is  sublimed. 

Benzule.  One  of  the  most  interesting  discoveries  lately  made  in 
vegetable  chemistry,  is  that  of  M.  M.  Wb'hler  and  Liebig,  of  the  radical 
of  berizoic  acid.  It  is  the  first  example  of  a  radical  consisting  of  three 
elements,  and  promises  to  throw  much  light  on  the  nature  of  the  vege- 
table principles  in  general. 

The  close  connexion  of  benzoic  acid  and  oil  of  bitter  almonds,  in 
which  crystals  of  the  acid  are  often  deposited,  as  it  was  supposed  from 
the  oxidizement  of  the  oil,  led  the  above  named  chemists  to  analyze  it, 
when  they  found  it  to  consist  of2O-f-6H-f-14C  ;  that  is,  it  contains  one 
atom  of  hydrogen  more,  and  one  of  hydrogen  less,  than  benzoic  acid. 
Th^y  consider  both,  therefore,  to  be  compounds  of  the  same  radical 
composed  of  2O-j-5H-f-14C,  which  they  propose  to  call  Benzule,  from 
the  Greek  ule,  matter  or  base.  If  this  radical  be  represented  by  Bz, 
then  Bz-f-O=benzoic  acid  and  Bz-f-H==oil  of  bitter  almonds. 

If  the  oil  be  exposed  to  a  current  of  chlorine,  there  are  formed  two 
products.  Cl-f-Bz  and  Cl-jkH,  chloride  of  benzule  and  muriatic  acid. 
With  hydrated  bases,  it  gives  a  benzoate  of  the  oxide  and  a  chloride  of 
the  metal.  Distilled  with  cyanide  of  mercury,  it  gives  a  cyanide  of 
benzule  and  a  chloride  of  mercury.  With  sulphuret  of  lead,  and  iodide 
and  bromide  of  potassium,  it  gives,  in  the  same  way,  a  sulphuret  and 
iodide  and  a  bromide  of  benzule,  while  the  chlorine  unites  with  the  me- 
tal. The  iodide  and  bromide  are  crystallizable  and  volatile,  and  all 
three  are  decomposed  by  water  and  bases  like  the  chloride. — Johnston's 
Report  on  Chemistry. 

REFERENCES.  Vogel,  on  Benzoic  Acid  in  Melilotus  Qffitinalis,  fyc.  Ann. 
of  Phil,  xvi.2^7.  Other  sources  of ,  Brandos  Jour,  xviii.  319.  Hisinger,  on 
the  Bznzontes,  Phil.  Ma. %.  \\.  Tromnisdorf  and  Berzelius,  on  the  same,  Ann* 
de  Chim.  xi.  and  xc.  Faraday,  iuBrande's  Jour.  vi.  159. 

Gallic  Acid.— Atom.  Num.  63—Symb.  3O+3H+6C. 

Discovered  by  Scheele  in  1786. 

STATE  AND  RROPERTIES.  It  exists  ready  formed  in  the  bark  of  many 
trees  and  in  gall-nuts. — When  pure  it  is  in  the  form  of  whitish  crystals  ; 
has  a  sour  taste  and  reddens  litmus  ;  is  soluble  in  twenty  .parts  of  water 
at  6(P,  and  in  three  parts  at  2123.  and  is  also  soluble  in  alcohol  and 
ether  ;  when  heated  in  the  air  it  exhales  a  peculiar  smell,  and  at  a  high 
heat  takes  fire. 

With  lime-water,  gallic  acid  yields  a  brownish-green  precipitate,  which 
is  redissolved  by  an  excess  of  the  solution,  and  acquires  a  reddish  tint. 
It  is  distinguished  from  tannin  by  causing  no  precipitate  in  a  solution 
of  gelatine.  With  a  salt  of  iron,  it  forms  a  dark  blue-coloured  corn- 
pound,  which  is  the  basis  of  ink.  The  finest  colour  is  procured  when 
the  peroxide  and  protoxide  of  iron  are  mixed  together.  This  charac- 
ter distinguishes  gallic  acid  from  every  other  substance  excepting 
tannin. 


374  VEGETABLE    SUBSTANCES. 

When  the  impure  acid  obtained  from  the  gall-nut  by  sublimation  is 
exposed  to  a  temperature  of  35(P  F.  the  mass  enters  into  fusion  and  a 
volatile  matter  passes  over  and  condenses  on  cool  surfaces  in  the  form 
of  delicate  long  scaly  crystals.  These  constitute  the  Pyrogullic  acid 
of  Braconnot. 

PREPARATION.  Pure  gallic  acid  may  be  obtained,  according  to  Dq- 
bereiner,  in  a  few  minutes  by  the  following  process  :  A  concentrated 
decoction  of  gall-nuts,  mixed  with  a  little  acetic  acid  to  decompose  the 
gallate  of  lime,  is  shaken  for  one  minute  with  a  quantity  of  ether. — 
The  gallic  acid  is  taken  up  by  the  ether,  and  by  spontaneous  evapora- 
tion on  a  watch  glass  is  obtained  in  small  colourless  prisms.  If  longer 
digested,  the  liquid  separates  into  three  portions.  The  lightest  con* 
tains  the  gallic  and  acetic  acids,  if  the  latter  be  present  in  excess  ;  the 
next,  an  ethereal  solution  of  tannin  ;  and  the  heaviest,  the  water  and 
extractive  matter. 

The  salts  of  gallic  acid,  called  Gallates,  have  been  imperfectly  ex- 
amined. The  gallates  of  potassa,  soda,  and  ammonia,  are  soluble  in 
water  ;  but  most  of  the  other  gallates  are  of  sparing  solubility.  On 
this  account  many  of  the  metallic  solutions  are  precipitated  by  gallic 
acid. 

REFERKNCES.  B.  La  Grange  s  fids  towards  a  history  of  Gallic  Acid, 
containing  a  nofic?  of  various  processes  for  obtaining  it,  and  of  sew  if  t)te 
Gallates,  Ann.  de  Chim.  or  Reperl.  of  Arts.  Zd  ser  ii.  227,  28  >.  Thenard, 
Traite  de  Chim.  iii.  f>53.  Berzelins,  Ann.  of  Phil,  v  17<\ 

Ellagic  Add — Exists,  according  to  Braconnot,  along  with  the  gallic 
acid,  in  infusion  of  galls,  but  its  characters  have  been  but  imperfectly 
examined.  Its  name  is  derived  from  the  word  guile,  reversed. — See 
Vauquelin,  Ann.  de  (.him.  ct  de  Fhys.  xxxvii.  175.  Thcnard,  Traite  dc 
Chim.  iii.  C55. 

The  remaining  vegetable  acids  are  arranged  alphabetically. 

Aspartic  Add. — Discovered  and  its  properties  investigated  by  M.  M. 
Henry  and  Plisson,  in  1829.  A  white  powder  consisting  of  minute 
crystals,  having  a  slightly  acid  taste,  arid  reddening  the  infusion  of 
litmus.  Obtained  by  mixing  acetate  of  lead  with  the  juice  of  the  shooty 
of  asparagus,  washing  the  insoluble  salt  which  is  produced,  mixing  it 
with  water,  decomposing  by  a  current  of  sulphuretted  hydrogen  gas, 
and  evaporating  the  solution. — Thomson  s  ln.org.  them.  ii.  100. 

Bidetic  Acid — Discovered  by  Braconnot  in  the  Holetus  Pscudo-igni- 
arius.  It  is  in  the  fortn  of  prismatic  crystals  ;  reddens  litmus,  and 
unites  with  some  bases.  — Braconnot  on  Boletic  Add  and  the  Boletatcs, 
Ann.  of  Phil.  ii.  469. 

Camphoric  Add. — Obtained  from  camphor  by  repeated  distillations 
with  nitric  acid.  It  assumes  the  form  of  plumose  crystals,  has  a  sour 
and  somewhat  bitter  taste,  and  an  aromatic  odour  ;  reddens  litmus  ; 
is  very  sparingly  soluble  in  cold  water — more  so  in  hot ;  is  very  solu- 
ble in  hot  alcohol  ;  when  thrown  upon  coals  is  completely  exhaled  in 
the  form  of  thick,  white  and  aromatic  fumes. — For  Licbig's  expwimmts 
on  the  composition  of  this  add.  sec  J<  vr.  of  the  Roy.  Jnst.  ii.  630.  Bu- 
cholz  on  Camphoric  Acid  and  the  Camphor ates,  Ann.  of  Phil.  ii.  313. 

Carbazotic  Acid. — Obtained  by  the  action  of  nitric  acid  upon  indigo- 
or  silk.  When  pure  this  acid  is  in  the  form  of  brilliant  crystalline 
plates,  of  a  yellow  colour  ;  is  soluble  readily  in  alcohol  and  ether,  but 
sparingly  soluble  in  cold  water  ;  is  fused  and  volatilized  by  heat,  with- 


VEGETABLE  SUBSTANCES.         375 

out  decomposition,  but  when  suddenly  exposed  to  strong  heat,  in- 
flames without  explosion,  and  burns  with  a  yellow  flame  ;  reddens  lit- 
mus paper,  and  is  extremely  bitter. — Brandes  Jour.  N.  S.  ii.  210,  and 
ill.  490,  ichere  several  compounds  of  this  acid,  icith  bases,  are  also  described. 

Chloroxalic  Acid. — When  crystallizable  acetic  acid  is  put  into  a  glass 
vessel  full  of  dry  chlorine,  and  exposed  for  a  day  to  bright  sunshine, 
muriatic  acid  gas  is  generated,  and  during  the  night  chloroxalic  acid  is 
deposited  in  dendritic  crystals  or  small  rhombic  scales.  Jn  order  to  ob- 
tain it  pure,  the  chlorine  should  be  in  excess,  and  the  gases  subsequent- 
ly expelled  from  the  flask  by  dry  air.  The  new  acid  is  very  volatile 
and  deliquescent,  and  when  evaporated  in  vacua  yields  rhombic  crys- 
tals.— Dumas. 

Caincic  Acid — Discovered  by  Pelletier  and  Caventou  in  the  cainca 
root  Chiococca  racemosa,  to  which  the  medical  properties  of  the  root 
are  supposed  to  be  owing.  It  may  be  prepared  by  acidulating  by  mu- 
riatic acid  a  very  concentrated  decoction  of  the  root ;  and  allowing  the 
liquor  to  repose  for  several  days,  when  the  acid  gradually  crystallizes. — 
Bcrzc.lius,  Traite  dc  Chirn.  v.  99. 

Cramtric  Acid,  is  obtained  according  to  M.  Peschier,  fronfthe  astrin- 
gent root  of  the  Crameria  triandra. — Ann.  dc,  Chim. 

Croconic  Acid. — The  gray  flaky  substance  which  deposits  in  cool  ves- 
sels during  the  preparation  of  potassium  from  cream  of  tartar,  when 
treated  with  water,  becomes  red,  and  on  exposure  to  the  air  a  reddish 
yellow  solution  is  formed,  which  by  gentle  evaporation  yields  croco- 
nate  of  potassa  in  crystals  of  the  same  colour  as  the  solution  :  the 
residual  liquid  contains  bicarbonate  and  oxalate  of  potassa.  In  order 
to  separate  croconic  acid,  these  crystals,  purified  by  a  second  crystal- 
lization and  reduced  to  fine  powder,  are  put  into  absolute  alcohol  to 
which  sulphuric  acid  of  the  specific  gravity  1-78,  in  quantity  insuffi- 
cient for  combining  with  all  the  alkali  of  the  croconate,  is  added.  The 
mixture  is  gently  warmed  during  several  hours,  and  frequently  shaken, 
until  a  drop  of  the  solution,  mixed  with  muriate  of  baryta,  causes  no 
turbidity.  The  yellow  alcoholic  solution  of  croconic  acid  is  then  sepa- 
rated from  sulphate  of  potassa  by  filtration,  and  the  acid  obtained  by 
expelling  the  alcohol.  By  solution  in  water  and  spontaneous  evapo- 
ration, croconic  acid  yields  transparent  prismatic  crystals  of  a  yellow 
colour,  which  are  inodorous,  have  an  astringent  taste,  redden  litmus, 
and  neutralize  alkaline  bases  ;  the  acid  as  well  as  its  salts  are  decom- 
posed at  a  high  temperature,  giving  a  deposit  of  charcoal.  According 
to  the  analysis  of  Gmeliri,  the  discoverer,  this  acid  consists  of  5  atoms 
carbon  -}-4  atoms  oxygen.  — Gmelin's  Handbuch. —  Turner's  Ghent.  4th  ed. 

Igasuric  Acid — Discovered  by  Pelletier  and  Caventou,  in  combina- 
tion with  strychnine,  in  the  SfryrJmos  Ignatii,  and  Strychnos  Nux 
Vomica,  though  its  existence,  as  different  from  all  other  acicte,  is  doubt- 
ful, [t  closely  resembles  the  meconic  acid,  but  does  not,  like  that, 
produce  a  red  colour  when  added  to  salts  of  iron  ;  crystallizes  in  small 
hard  crystals  ;  has  an  acid  and  very  styptic  taste  ;  is  soluble  in  water 
and  in  alcohol. — Ann.  de  Chim.  etdc  Phys.  x.  142.  Urc's  Chem.  Diet.  56. 

Itidigotic  Acid — First  described  by  Chevreul,  and  is  obtained  by  the 
action  of  nitric  acid  upon  indigo.  It  appears  to  be  distinct  from  the 
carbazotic  acid  formed  by  a  similar  process. 

Kinic  Acid,  is  found  in  the  bark  of  the  Cinchona  ;  it  is  difficultly 
crystallizable  ;  has  a  very  acid  taste,  but  when  pure  wholly  destitute 
of  bitterness  ;  reddens  litmus  permanently  ;  is  very  soluble  in  water  ; 


376          VEGETABLE  SUBSTANCES. 

is  not  altered  by  exposure  to  air,  and  forms  no  precipitates  with  the 
salts  of  mercury,  lead  or  silver. — Vauquelin,  in  Ann,  de  Chim.  lix.  162. 
Henry,  ii.  256. 

Laccic  Acid — Obtained  from  the  White  Lac  of  Madras,  by  Dr.  John* 
It  occurs  in  crystals  of  a  wine-yellow  colour  ;  has  a  very  sour  taste  ; 
is  soluble  in  water,  alcohol  and  ether ;  forms  white  precipitates  in  so- 
lutions of  lead  and  mercury,  but  has  no  effect  upon  lime-water,  nor  the 
nitrates  of  silver  and  baryta.  It  should  in  strictness  be  classed  among 
the  animal  acids. — A  full  account  of  the  properties  of  this  acid  and  of 
the  substance  that  affords  it,  may  be  found  in  Dr.  Pearson's  paper,  in  the 
Phil.  Trans.  1794. 

Lactucic  Acid — Discovered  by  Pfaffin  the  juice  of  the  Lncluca  Virosa. 
It  is  obtained  by  precipitating  the  clarified  juice  by  sulphate  of  copper 
or  acetate  of  lead,  washing  the  precipitate  and  decomposing  it  by  sul- 
phuretted hydrogen.  By  the  evaporation  of  the  liquor  the  lactucic 
acid  is  deposited  in  colourless  crystals.  It  closely  resembles  oxalic  acid, 
but  differs,  in  producing  an  abundant  green  precipitate  in  solutions  of 
the  neutral  salts  of  iron, — and  a  brown  precipitate  with  the  solution  of 
sulphate  of  copper. — Berzelius,  Traite  dc  Chim.  v.  97. 

Meconic  Acid. — This  acid  is  found  in  opium,  combined  with  mor- 
phine. It  occurs  in  crystals  of  various  forms,  which  fuse  at  212°  F., 
and  sublime  without  decomposition  ;  reddens  litmus  ;  is  very  sour  ;  is 
soluble  in  water  and  alcohol ;  produces  an  intense  red  colour  with  so- 
lutions of  the  peroxide  of  iron,  without  causing  any  precipitation. — 
For  a  good  account  of  Meconic  Acid,  and  the  Meconiates,  see  Ure's  Chem. 
Diet.  4th  ed.  Dr.  Hares  process  for  obtaining  the  acid  will  be  found  in 
Sill.  Jour.  xii.  293. 

MtUitic  Acid. — Found  in  a  rare  substance  called  Honey-stone,  occa- 
sionally met  writh  in  Thuringia.  in  Germany.  It  crystallizes  in  hard 
prisms,  or  in  fine  needles,  forming  sometimes  by  their  re-union,  a  glo- 
bular mass  ;  has  a  taste  first  sour  and  then  bitter  ;  is  not  very  soluble 
in  water  ;  when  placed  upon  a  hot  metallic  plate  it  gives  off  gray 
fumes  which  are  without  odour. — Ures  Chem.  Diet. 

Moric  or  Moroxylic  Add— Discovered  by  Klaproth,  and  combined 
with  lime,  exists  in  the  bark  of  the  Morus  Alba,  L.,  or  white  mulberry. 
It  crystallizes  in  fine  needles  ;  has  the  taste  of  succinic  acid  ;  reddens 
litmus  ;  is  not  altered  by  exposure  ;  is  soluble  in  water  and  alcohol ; 
and  when  heated  in  a  retort  is  partly  decomposed. — Klaproth,  in  Nich- 
olson's Jour.  vii.  129.  Henry,  ii.  253. 

Mucic  or  Saccholactic  Acid — Discovered  by  Scheele  in  1780.  and  ob- 
tained by  the  action  of  nitric  acid  upon  gum,  manna  and  the  sugar  of 
milk.  When  pure  this  acid  occurs  in  the  form  of  white  crystals  ;  has 
a  slightly  acid  taste,  and  reddens  litmus  feebly  ;  is  soluble  in  sixty 
times  its  weight  of  boiling  water,  and  insoluble  in  alcohol  ;  when 
heated  it  is  decomposed,  and  yields  a  volatile  white  substance,  which 
has  been  called  Pyro-mucic  Acid. — On  this  acid  and  the  Mucates,  see  The- 
nard,  Traite  de  Chim.  iii.  701. 

Pectic  Acid. — This  acid  is  found  in  all  vegetables  ;  it  occurs  in  the 
form  of  a  colourless  jelly  ;  has  no  odour,  and  a  slightly  acid  taste  ;  is 
nearly  insoluble  in  hot  water  as  well  as  cold  ;  possesses  the  remarka- 
ble property  of  gelatinizing  large  masses  of  sugar.  It  was  discovered 
by  Braconnot,  though  it  is  still  somewhat  doubtful  whether  it  is  a  dis- 
tinct acid. — Bmcomwt,  in  Ann.  de  Chim.  et  de  Phys.  xxviii.  173.  xxx. 


VEGETABLE    SUBSTANCES.  377 

96.     Thcnard,  Traite  de  Ckim.  iii.  669.     Dr.  Torrey  on  the  Pectic  Acid, 
and  its  identity  with  Sclerotin,  N.  Y.  Med.  and  Phys.  Jour.  vi.  481 . 

The  Phosphoric  and  Hydrocyanic  rfcids  are  also  found  in  vegetables. 
The  former  in  all  the  varieties  of  grain,  in  combination  chiefly  with 
potassa  and  lime.  The  latter  may  be  distilled  from  bitter  almonds, 
from  the  leaves  of  the  laurel,  &c. — Saussure,  in  Nicholson's  Jour.  xxv. 
279.  Vauquelm,  Jinn,  de  Chim.  xlv.  206. 

Suberic  Acid. — Formed  by  digesting  cork  in  nitric  acid.  When  pure 
it  is  a  white  powder  ;  has  a  feeble  taste,  and  has  little  action  on  lit- 
mus ;  is  sparingly  soluble  in  cold  water,  very  much  so  in  boiling  water; 
exposed  to  gentle  heat  it  melts  like  fatty  matter. — Thenard,  Traite  de 
Chim.  iii.  714. 

Succinic  Acid. — Obtained  by  distillation  from  amber.  When  perfect- 
ly pure  it  is  white,  transparent,  and  crystallizes  in  prisms  ;  has  a  sour 
and  somewhat  acrid  taste,  and  reddens  litmus  ;  is  not  altered  by  ex- 
posure;  is  sparingly  soluble  in  water  ;  when  exposed  to  heat  it  fuses, 
undergoes  decomposition,  and  in  part  sublimes,  emitting  a  very  pecu- 
liar and  characteristic  odour. 

The  compounds  of  this  acid  with  bases,  called  Succinates,  have  been 
but  little  examined.  The  Succinate  of  Ammonia,  easily  formed  by  the 
direct  union  of  its  elements,  is  employed  for  separating  iron  from  man- 
ganese, the  succinate  of  the  peroxide  of  iron  being  quite  insoluble  in 
water,  provided  the  solutions  are  neutral.  The  succinate  of  manga- 
nese, on  the  contrary,  is  soluble. — Berzelius,  Ann.  of  Phil.  ix.  108. — 
John,  same  icork,  xv.  388. 

Ulmic  Acid. — The  substance  formerly  called  Ulmin,  and  shown  to  be  a 
distinct  acid  by  Boullay  in  1830.  It  exists  ready  formed  in  bark,  and 
makes  its  appearance  in  a  variety  of  vegetable  decompositions.  It 
constitutes  the  essential  ingredient  of  peat  and  of  umber,  and  what  is 
usually  called  vegetable  manure. — Ann.  de  Chim.  et  de  Phys.  xliii.  273. 

Valerianic  Acid — Discovered  by  Grote  in  the  root  of  the  Valeriana 
officinalis.  It  is  colourless,  oleaginous — has  an  acid,  piquant  odour. 
It  combines  with  bases  and  forms  Valerianates ,  which  are  distinguished 
by  a  peculiar  sweetish  taste. 

Zumic  Acid — Discovered  by  Bracconnet  in  several  vegetable  substan- 
ces which  have  undergone  the  acetous  fermentation.  It  appears  from 
the  observations  of  Vogel  to  be  the  lactic  acid. — Ann.  of  Phil.  xii. 

SECTION   II. 

VEGETABLE  SAL1FIABLE  BASES  OR  ALKALIES. 

Under  this  head  are  classed  all  those  proximate  vegetable  princi- 
ples capable  of  uniting  with  acids,  and  of  forming  with  them  saline 
compounds. 

The  existence  of  this  class  of  bodies  was  discovered  by  Sertuerner, 
in  1805,  but  they  excited  no  attention  until  about  1816.  Since  that 
time  this  department  has  been  cultivated  with  much  success  by  seve- 
ral chemists,  but  especially  by  M.  Robiquet,  and  M.  M.  Pelletier  and 
Caventou. 

The  vegetable  alkalies,  according  to  the  researches  of  Pelletier  and 
Dumas,  consist  of  carbon,  hydrogen,  oxygen  and  nitrogen.  [Ann.  de 
Chim.  et  dc  Phys.  xxiv.]  They  are  all  solid,  white,  bitter  or  acrid, 


378  VEGETABLE  SUBSTANCES. 

without  odour,  heavier  than  water,  and  mostly  crystalline  ;  they 
change  vegetable  blues  to  green  ;  are  insoluble,  or  nearly  so,  in  cold 
water,  but  soluble  in  alcohol,  especially  if  hot ;  most  of  them  are  poi- 
sonous, and  many  are  valuable  in  medicine. 

These  substances  aie  never  found  in  a  free  state  in  plants,  but  ap- 
pear in  every  case  to  be  combined  with  an  acid,  forming  a  salt,  more 
or  less  soluble  in  water.  And  the  process  for  separating  them  which 
is  generally  applicable,  is  to  digest  or  macerate  the  substance  contain- 
ing the  alkali,  in  a  large  quantity  of  water,  and  to  add  to  the  solution 
a  more  powerful  salifiable  base,  as  potassa,  soda  or  ammonia,  or  to 
boil  it  for  a  few  minutes  with  pure  lime  or  magnesia.  The  vegetable 
alkali  being  thus  separated  from  its  union  with  the  acid,  and  being  in- 
soluble in  water,  is  precipitated.  This  precipitate,  mixed  with  some 
animal  charcoal,  is  then  dissolved  in  hot  alcohol,  and  the  solution  fil- 
tered while  hot  and  evaporated  ;  arid  the  pure  alkali  is  thus  obtained. 

According  to  Serullas,  the  vegetable  alkalies  may  be  precipitated  by 
iodic  acid,  which  he  considers  a  very  delicate  test  of  their  presence  in 
solutions. — Jinn,  de  Cliim.  xlv.  or  Jour,  of  Ike  Roy.  Inst.  ii.  615. 

Different  opinions  are  still  entertained  concerning  the  nature  of  the 
vegetable  alkalies.  They  may  be  reduced  to  the  following : 

1.  That  they  combine  with  acids  in  the  same  manner  as  metallic  ox- 
ides, and  give  birth  to  anhydrous  salts  composed  of  the  two  bodies  in 
contact.     This  is  the  most  generally  received. 

2.  That  they  contain  a  certain  quantity  of  ammonia  to  which  they 
owe  their  powers  as  bases,   and   with  which  some  organic  matter  is 
combined  in  the  same  way  as  many  vegetable  substances  are  united 
with  sulphuric  acid  ;  and  that  this  substance  enters  with  the  ammonia 
into  the  salt  formed. 

3.  That  the  vegetable  alkalies  like  ammonia  have  the  power  of  act- 
ing as  bases  only  when  combined  with  water  ;  in  which  case  the  pro- 
portions in  which  they  saturate  the  acids  depend  upon  the  quantity  of 
water.     Or  in  other  words,   the  vegetable  alkalies  considered  in  this 
point  of  view,  only  combine  with  the  hydrous  acids,  and  without  set- 
ting at  liberty  the  water  contained  in  these  acids. — Bcrzdius,  Traitc  de 
Chim.  v.  123. 

Morphine. 

This  is  the  active  principle  of  opium,  (Papaver  Somnifcrum ,  L.)  in 
which  it  is  combined  with  various  other  principles.  It  occurs  in  crys- 
tals of  a  brilliant  lustre,  which  are  mostly  irregular  six-sided  prisms, 
with  diedral  summits,  but  the  primary  form  of  which,  according  to 
Brooke,  is  a  right  rhombic  prism  ;  it  is  insoluble  in  cold,  and  sparingly 
soluble  in  boiling  water;  soluble  in  alcohol,  and  in  solution  intensely 
bitter  ;  has  an  alkaline  reaction,  and  forms  salts  with  acids,  which  are 
mostly  capable  of  crystallizing. 

PREPARATION.  Various  processes  have  been  proposed  for  separating 
this  alkali.  That  of  Robiquet,  which  is  probably  the  best,  is  to  boil 
the  concentrated  infusion  of  a  pound  of  opium  for  a  quarter  of  an  hour 
with  about  150  grains  of  pure  magnesia.  A  grayish  crystalline  preci- 
pitate results,  which  consists  ot  meconate  of  magnesia,  morphine, 
iiarcotine,  colouring  matter  and  the  excess  of  magnesia.  This  pow- 
der is  collected  on  a  filter,  edulcorated  with  cold  water,  and  then  di- 
gested at  a  temperature  of  120°  or  139  J  F,  in  dilute  alcohol,  which  ro- 


VEGETABLE  SUBSTANCES.         379 

moves  the  narcotine,  and  the  greater  part  of  the  colouring  matter. 
The  morphine  is  then  taken  up  by  concentrated  boiling  alcohol,  and  is 
deposited  in  crystals  on  cooling. 

A  convenient  process,  suggested  by  Dr.  Thomson,  is  to  precipitate 
the  morphine  by  ammonia,  and  to  purify  it  by  solution  in  acetic  acid, 
and  digestion  in  animal  charcoal,  deprived  of  phosphate  of  lime  by 
muriatic  acid. — Ann.  of  Phil.  xv.  471. 

ACTION  ON  THE  ANIMAL  ECONOMY.  It  appears  that  notwithstanding  the 
insolubility  of  morphine,  it  is  the  narcotic  principle  of  opium.  Direct 
experiments  have  sufficiently  proved  this.  If  for  example,  we  make  a 
solution  of  this  substance  in  oil,  we  perceive  violent  narcotic  effects, 
even  in  a  small  dose,  such  as  a  quarter  or  half  a  grain,  but  these  are 
still  more  marked  when  the  morphine  is  combined  with  acids,  probably 
because  its  salts  are  more  soluble  than  it  is  itself  in  an  uncombined 
state. 

Salts  of  MorpJiine. 

These  salts  may  be  readily  obtained  by  dissolving  pure  morphine  in 
dilute  acid  and  evaporating  the  solution.  They  have  long  been  used 
for  medicinal  purposes,  and  are  found  to  possess  all  the  good  qualities 
of  opium,  without  its  inconveniences. 

Muriate  of  Morphine — Usually  crystallizes  in  tufts  of  acicular  crys- 
tals, which  are  neutral  and  anhydrous.  It  is  obtained  by  the  direct 
action  of  muriatic  acid  gas  upon  morphine,  or  by  dissolving  the  alkali 
in  dilute  muriatic  acid.  The  process  employed  by  Dr.  A.  T.  Thom- 
son is  to  decompose  the  aqueous  solution  of  opium  by  muriate  of  ba- 
ryta, of  which  a  quantity  is  used  exactly  sufficient  for  precipitating  the 
ineconic  acid.  The  muriates  of  morphine  and  narcotine  are  then  sepa 
rated  by  crystallization.  This  salt  has  recently  come  into  use  in  medi- 
cal practice  in  consequence  of  its  being  more  uniform  in  its  constitu- 
tion, than  the  other  salts. — [For  a  detailed  account  of  the  mode  of 
preparing  this  salt,  see  Edin.  Med.  and  Sitrg.  Jour.  Nos.  107  and  lll.i 

Sulphate  of  Morphine,  crystallizes  in  silky  tufts,  much  resembling 
sulphate  of  quinine,  from  which  it  may  be  distinguished  by  its  becom- 
ing red  when  heated  with  concentrated  nitric  acid.  It  may  be  obtain- 
ed by  the  direct  union  of  sulphuric  acid  with  morphine. 

Acetate  of  Morphine — Obtained  by  dissolving  morphine  in  acetic  acid. 
In  order  to  obtain  it  in  the  solid  state,  it  must  be  evaporated  to  dry- 
ness.  and  in  this  process  some  of  the  acid  is  usually  expelled.  It  is 
therefore  necessary  that  it  should  be  preserved  in  the  form  of  solution, 
and  care  should  be  used  that  the  acid  is  in  excess. 

The  compound  called  Black  Drop,  consists  of  opium  combined  with 
some  vegetable  acid,  generally  in  an  impure  state.  Those  most  com- 
monly used  are  the  citric  and  acetic,  combined  with  aromatics  and 
sweet  substances. 

^REFERENCES.  For  affecting  Ace  fate  cf  Morphine  when  given  for  criinina 
purposes,  a  process  has  been  described  by  M.  Lasnaignf,  for  which  see  Aim. 
de  Chim.  et  de  Phys.  xxv.  102,  or  Turner's  Chem.  7f,8  See  also  Hare's  Com 
pe7id.  206.  For  the  medicinal  preparations  of  Morphine  and  its  Salts,  see 
Magendie  s  Formulary,  Carpenter  on  the  Salts  of  Morphine,  Chapman's 
Jvur.  v  213. 


380  VEGETABLE  SUBSTANCES. 

Narcotinc. — This  substance,  though  not  regarded  as  a  vegetable  al- 
kali,* may  be  conveniently  noticed  in  connection  with  morphine.  It 
dissolves  in  ether  and  alcohol,  the  latter,  though  diluted,  acting  as  a 
solvent  for  it  by  the  aid  of  heat ;  and  it  crystallizes  from  its  solutions 
in  the  form  of  fine  needles  or  rhomboidal  prisms  ;  ^t  exerts  no  action 
on  vegetable  colours ',  is  without  taste  or  smell. 

Narcotine  is  easily  prepared  by  evaporating  an  aqueous  infusion  of 
opium  to  the  consistence  of  an  extract,  and  digesting  it  in  sulphuric 
ether.  From  this  solvent  it  may  be  obtained  by  evaporation,  in  the 
form  of  crystals.  In  the  same  manner  morphine  may  be  purified  from 
narcotine.  But  an  easier  process  is  founded  upon  the  property  dis- 
covered by  Duflos,  that  carbonate  of  potassa  precipitates  narcotine, 
but  not  morphine. 

The  unpleasant  stimulating  properties  of  opium  are  attributed  by 
Magendie  to  the  presence  of  narcotine,  the  ill  effects  of  which,  ac- 
cording to  the  experiments  of  the  same  physiologist,  are  in  a  great 
degree  counteracted  by  acetic  acid.  These  results,  though  they  re- 
quire confirmation,  render  it  probable  that  the  superiority  assigned  to 
the  Black  Drop  over  the  common  tincture  of  opium  of  the  Pharmaco- 
poeia, is  owing  to  the  vegetable  acids  which  enter  into  its  composition. 

Some  physicians,  however,  discard  the  medical  distinctions  gene- 
rally drawn  between  morphine  and  narcotine,  and  assert  that  denar- 
cotized  opium  or  laudanum,  in  its  effect,  differs  in  no  respect  from 
common  laudanum,  except  in  being  considerably  weaker. — See  the  views 
of  Prof.  Tully  and  others,  in  Silliman's  Chem.  ii.  491. 

Cinchonine. 

Discovered  by  Dr.  Duncan  jun.  in  1803,  though  its  alkaline  nature 
was  first  settled  by  Pelletier  and  Caventou,  in  1820.  It  exists  in  the 
Cinchona  condaminea,  or  pale  bark,  combined  with  kinic  acid.  It  is 
white  and  crystalline,  requires  2,500  times  its  weight  of  boiling  water 
for  solution,  and  is  insoluble  in  cold  water  ;  is  soluble  in  boiling  alco- 
hol, and  in  small  quantity  in  oil  and  ether  ;  has  a  bitter  taste,  though 
scarcely  sensible  unless  in  solution  ;  it  unites  with  all  the  acids,  and 
forms  salts.  It  is  obtained  by  a  process  similar  to  that  described  for 
obtaining  morphine. — Edin.  New  Dispensary,  \}th  cd.  299. 

Both  the  Sulphate  and  Slcetate  of  Cinchonine  are  employed  in  medi- 
cine ;  the  first  of  these  salts  is  very  soluble  in  water,  the  second  much 
less  so  ;  but  an  excess  of  acid  dissolves  it  readily. — For  a  description 
of  several  salts  of  cinchonine.  see  Berzelius,  Traits,  de  Chim.  v.  164. 

Quinine. 

Discovered  by  Pelletier  and  Caventou.  Exists,  combined  with  kin- 
ic acid,  in  the  Cinchona  cordifolia,  or  yellow  bark,  and  together 
with  cinchonine  in  the  Cinchona  oblongifolia,  or  red  bark.  It  is  usu- 


ble  in  alcohol,  forming  a  solution  which  is  intensely  bitter,   and  pos- 


*  Berzelius,  however,  thinks  narcotine  should  be  ranked  among1  the  vegeta- 
ble alkalies,  because  it  possesses  the  property  of  combining  with  acids  and 
forming  salts,  some  of  which  are  crystalline. — Traite  de  Chim.  v.  137. 


VEGETABLE  SUBSTANCES.          381 

sessing  distinct  alkaline  reaction  ;  is  also  soluble  in  ether,  but  almost 
insoluble  in  water ;  is  distinguished  from  cinchonine  by  its  habi- 
tudes with  acids,  and  by  the  different  properties  which  characterize  its 
salts. 

Salfikate  of  Quinine.— Though  quinine  combines  with  most  of  the 
acids,  the  form  in  which  it  is  commonly  exhibited  is  that  of  the  Sul- 
phate. This  salt,  which  consists  of  90  parts  of  the  alkali  and  10  of 
the  acid,  crystallizes  in  delicate  white  needles,  having  the  appearance 
of  amianthus.  It  is  less  soluble  in  water  than  thj6  sulphate  of  cincho- 
nine, but  is  very  bitter.  It  dissolves  readily  in  Strong  alcohol  by  the 
aid  of  heat,  a  character  which  affords  a  useful  test  of  its  purity.  One 
grain  of  the  sulphate  of  quinine,  when  pure,  will  render  nearly  a 
pound  and  a  half  of  water  sensibly  bitter. — See  R.  I  hillips  on  the  means 
of  ascertaining  the  purity  vf  Sulphate  of  Quinine)  Phil.  Mag.  and  Jinn. 
hi.  111. 

The  presence  of  cinchonine  in  the  sulphate  of  quinine  may  be  de- 
tected by  the  following  method.  A  grain  of  the  salt  in  fine  powder  is 
shaken  with  a  dram  of  ether,  and  a  dram  of  ammonia  is  added  and  the 
whole  well  shaken.  If  no  cinchonine  be  present,  the  line  of  separation 
of  the  two  fluids  is  clean  ;  if  the  smallest  quantity  be  present,  it  is 
deposited  in  this  line. — Kindt,  in  Urandes  Archiv. — Johnston's  Report. 

Strychnine. 

Discovered  in  1818,  by  Pelletier  and  Caventou,  in  the  fruit  of  the 
Strychnos  ignatia  and  Strycknos  nux  vomica,  in  which  it  is  combined 
with  igasuric  acid  ;  it  has  since  been  extracted  by  the  same  chemists 
from  the  famous  Upas  of  Java.  It  occurs  in  the  form  of  small  four-sided 
prisms  ;  it  is  intolerably  bitter,  and  leaves  an  impression  on  the  or- 
gans of  taste  like  that  of  some  of  the  metallic  salts  ;  has  no  smell,  and 
is  not  changed  by  exposure  to  air  ;  it  is  nearly  insoluble  in  water,  re- 
quiring more  than  6000  times  its  weight  of  cold,  and  2500  of  boiling 
water  for  solution  ;  has  a  distinct  alkaline  reaction  and  forms  salts 
with  acids,  most  of  which  are  soluble  in  water. — Pelletier  and  Caven- 
lou,  in  Ann.  de  Chim.  ct.  de  Pkijs.  x.  and  xxvi.  Henry,  in  Jour,  de  Phar. 
viii.  401. 

Strychnine  is  one  of  the  most  virulent  poisons  hitheito  discovered, 
and  is  the  poisonous  principle  of  the  substance  in  which  it  is  contain- 
ed. Its  energy  is  so  great,  that  half  a  grain  blown  into  the  throat  of 
a  rabbit  occasioned  death  in  the  course  of  five  minutes.  Its  operation 
is  always  accompanied  with  symptoms  of  locked  jaw  and  other  teta- 
nic affections. — See  Magendie  and  Christison  on  Poisons,  637. 

The  salts  of  strychnine,  in  consequence  of  their  greater  solubility, 
are  more  active,  and  consequently  more  intensely  poisonous  than 
their  base.  They  are,  nevertheless,  employed  medicinally  in  small 
doses  with  decided  advantage, 

Brucine. 

Discovered  by  Pelletier  and  Caventou,  in  the  Brucea  antidystnterica, 
and,  in  small  quantities,  also  in  the  Strycknos  nux  vomica.  It  crys- 
tallizes in  oblique  prisms,  the  bases  of  which  are  parallelograms  :  in 
taste  and  poisonous  qualities,  it  is  very  similar  to  strychnine,  but  is 
twelve  or  sixteen  times  less  energetic  than  that  alkali ;  it  is  soluble 

Y 


3S2          VEGETABLE  SUBSTANCES. 

both  in  hot  and  cold  alcohol,  especially  in  the  former  ;  and  it  crystal- 
lizes when  its  solution  is  evaporated  ;  is  soluble  also  in  dilute  alcohol, 
by  aid  of  heat,  and  on  this  property  is  formed  the  method  of  separat- 
ing it  from  strychnine  ;  it  is  more  soluble  in  water  than  most  of  the 
other  vegetable  alkalies,  requiring  only  850  times  its  weight  of  cold, 
and  500  of  boiling  water  for  solution. 

Emetine. 

Discovered  in  1817,  by  Pelletier,  and  is  found  in  the  Ccphaelis  Ipe- 
cacuanha, Willd.  and  VioLi  Jpecncutmha.  When  pure  it  is  white  and  pul- 
verulent, and  not  deliquescent  ;  lias  a  bitter  and  disagreeable  taste ; 
is  sparingly  soluble  in  cold,  but  more  freely  in  hot  water  ;  is  insolu- 
ble in  ether,  but  readily  soluble  in  alcohol ;  has  a  distinct  alkaline  re- 
action, arid  neutralizes  acids,  but  its  salts  are  little  disposed  to  crystal- 
lize ;  its  effects  appear  to  be  neutralized  by  decoction  of  galls. — Ma- 
gendie's  Formularly,  40. 

It  is  to  this  principle  that  ipecacuanha  owes  its  emetic  properties. 

Veratrint. 

This  alkali,  discovered  by  Pelletier  and  Caventou,  in  1819,  exists 
combined  with  gallic  acid,  in  the  seeds  of  the  Veratrum  sabadilla, 
Itetz,  and  the  roots  of  Vcnitrum  album,  L  or  white  hellebore  ;  and  Col- 
chicum  autumnale,  L.  or  meadow  saifron.  It  is  white,  pulverulent, 
inodorous,  and  of  an  acrid  taste  ;  requires  1000  times  its  weight  of 
boiling,  and  still  more  of  cold  water  for  solui  on  ;  is  very  soluble  in 
alcohol,  and  may  also  be  dissolved,  though  less  readily,  by  means  of 
ether  ;  has  an  alkaline  reaction,  and  neutralizes  acids,  but  it  is  a 
weaker  base  than  morphine,  quinine  or  strychnine  ;  it  acts  with  singu- 
lar energy  on  the  membrane  of  the  nose,  exciting  violent  sneezings 
though  in  very  minute  quantity  ;  when  taken  internally  in  very  small 
doses,  it  produces  excessive  irritation  of  the  mucous  coat  of  the  stomach 
and  intestines,  and  a  few  grains  were  found  to  be  fatal  to  the  lower 
animals. — Jour,  de  Phar.  vi.  Mugendies  Formulary,  61. 

.  ,»l 

Sangitfaarine. 

Discovered  by  the  late  professor  Dana,  of  New-York,  in  the  root  of 
the  Sanguinaria  canadensis,  L.  or  blood  root.  It  usually  occurs  in  the 
form  of  a  soft,  white  powder  ;  but  by  the  spontaneous  evaporation  of 
an  alcoholic  solution  may  be  obtained  in  masses  which  exhibit  a  crys- 
talline structure  ;  has  no  odour,  but  a  taste  bitter  and  afterwards 
acrid  ;  changes  the  blue  of  litmus  to  green,  the  yellow  of  turmeric  to 
brown  ;  combines  with  acids  and  forms  neutral  salts  of  a  red  colour. — 
See  Dana,  in  N.  Y.  Med.  and  Phys.  Jour.  vi.  218,  and  Dr.  Tully  and  Mr. 
A.  A.  Hayes,  in  SiUiman's  Chem.  ii.  503. 

According  to  Dr.  Tully  the  medicinal  virtues  of  blood  root  reside  in 
this  principle,  and  are  not  impaired  by  combination  with  acids.  It  is 
medicinally  deobstruent,  acrid,  narcotic  and  emetic.-  See  Professor 
Tally's  Prize  Dissertation  on  Sanguinaria,  in  the  American  Med.  JRecor 
der,  xiii. 


V 

VEGETABLE  SUBSTANCES.          383 

The  remaining  vegetable  alkalies  are  arranged  alphabetically. 

Atropine. — Discovered  by  Brandes,  in  the  Atropa  belladonna,  L.  ot 
deadly  nightshade.  When  pure  it  is  snow-white,  when  impure  yel- 
lowish ;  it  has  no  taste  ;  is  almost  insoluble  in  cold  water,  except  when 
recently  precipitated;  it  neutralizes  acids  and  forms  salts,  the  watery 
solutions  of  which  give  out  by  evaporation,  vapours  which  dilate  the 
pupil  of  the  eye  and  produce  violent  headache,  nausea  and  giddiness. 
— See  Ur&s  Chem.  Diet.  It.k  cd.  181. 

Buxine— Announced  by  Foure  as  an  alkali  existing  in  the  box,  Ruxus 
sempcrvirens.  It  has  a  bitter  taste  ;  is  insoluble  in  water,  but  soluble  in 
alcohol  and  in  small  quantity  in  ether. — Berzelius,  v.  191. 

Corydafine. — Discovered  by  M.  Wackenroder,  in  the  root  of  the  Fu- 
maria  cava,  Mil.  and  (lorydafotubcrosa,  De  Cande.  Ft  is  obtained  from 
its  alcoholic  solution  in  the  form  of  colourless  prismatic  crystals;  it 
acts  as  an  alkali  upon  vegetable  colours,  and  combines  with  acids, 
forming  extremely  bitter  salts  its  nitric  solution  becomes,  when  heat- 
ed and  concentrated,  of  a  blood-red  colour. — Phil.  Mug.  and  Ann.  iv. 
151. 

Crotonine. — Exists  according  to  Brandes  in  the  seed  of  the  Croton 
tiglium. — Bcrzelius,  v.  190. 

Curarine  — A  basis  discovered  by  Boussingault  and  Roulin,  in  a 
matter  which  the  natives  of  South  America  employ  in  poisoning  their 
arrows,  and  which  they  call  curara  or  urarL  Prepared  according  to 
the  process  of  Pelletier  and  Petroz,  it  is  an  uncrystallizable  yellowish 
mass,  which  has  a  very  bitter  taste,  and  deliquesces  upon  exposure  to 
the  air.  It  forms  neutral  salts  with  the  acids.  Its  poisonous  effects 
are  more  decided  than  those  of  the  curara  from  which  it  is  obtained. — 
Berzclius,  v.  181. 

Cynapine. — Discovered  by  Professor  Ficinus  of  Dresden,  in  the 
Aetllusn  Cynapium,  or  lesser  hemlock.  It  is  crystallizable,  and  soluble 
in  water  and  alcohol,  but  not  in  ether.  The  crystals  are  in  the  form  of 
a  rhombic  prism,  which  is  also  that  of  the  crystals  of  the  sulphate. — 
Turner. 

Daphnine. — A  basis  discovered  by  Vauquelin  in  the  Daphne  Mezcrium. 

Daturine. — Obtained  by  M.  Brandes,  from  the  Datura  stramojiium, 
L.  It  is  similar  to  atropine,  and  perhaps  indentical  with  it. 

Delphine  or  Delphinine. — Discovered  by  MM.  Feneulle  and  Las- 
saigne  in  the  Delphinium  stnphysagria,  L.  or  Stavesacre.  It  is  in  the 
form  of  a  white  powder,  crystallizing  when  moist,  but  becoming  opaque 
by  exposure  to  dry  air  ;  it  has  no  smell,  but  a  taste  at  first  bitter  and 
afterwards  becoming  acrid  ;  is  sparingly  soluble  in  water,  but  freely  so 
in  alcohol  and  ether ;  it  combines  with  many  acids  and  forms  neutral 
salts,  whose  taste  is  extremely  bitter  and  acrid ;  it  is  precipitated  by 
alkalies  in  the  form  of  a  white  jelly. — Ann.  de  Chim.  tt  de  Phys.  xii. 
Mtigendie. 

Digitaline. — Extracted,  by  M.  Le  Royer,  from  the  leaves  of  the  Di- 
gitalis pur  pur  ea,  L.  or  foxglove.  It  is  a  brown,  pasty  substance,  slowly 
restoring  the  blue  colour  of  reddened  litmus  ,  very  bitter  and  very  deli- 
quescent ;  it  is  difficultly  crystallizable  ;  but  seems  capable  of  crys- 
tallizing from  its  alcoholic  solution  ;  it  combines  with  acids,  and  has 
great  activity  on  the  animal  system. — Brandos  Jour,  xviii.  178. 


384         VEGETABLE  SUBSTANCES. 

Essenbcckine. — A  supposed  basis  discovered  by  Buchner.  in  Essen- 
beckia  febrifuga.  It  has  a  bitter  taste  like  quinine.  —  Berzelius,  v.  (90. 

Eupatorine. — A  basis  discovered  by  Riphini  in  the  Eupatoriujn  can- 
nauinum. — Bcrzelius,  v.  192. 

Hyoscyamine. — Extracted  by  Brandes,  from  the  Hyoscyamusniger,  L. 
or  black  henbane  ;  it  crystallizes  in  long  prisms,  is  not  easily  altered 
in  a  high  temperature,  even  when  heated  to  redness  with  charcoal; 
when  saturated  with  sulphuric  or  nitric  acid  forms  very  characteristic 
salts.  -Ann.  of  Phil.  xvi.  69. 

Nicotine. — The  active  principle  of  tobacco  Nicotiana  tabncum.  It  is 
a  volatile  alkali.  Its  solution  is  colourless  ;  has  the  peculiar  smell  of 
tobacco,  and  occasions  violent  sneezing  ;  has  an  acrid  taste,  and  pos- 
gesses  poisonous  qualities.—  (  VauqiLelin,  in  dim.  de  Cliim.  Ixxi.  139.) 
Berzelins  describes  several  salts  of  nicotine. 

Solanine. — Discovered  by  Desfosses.  and  exists  combined  with  malic 
acid  in  the  berries  of  the  Solanum  vign/jn,  L.  and  in  the  leaves  of  the 
Solunuin  dulcamara,  L.  When  pure  it  occurs  in  the  form  of  a  white, 
opaque,  and  sometimes  pearly  powder;  it  has  no  smell,  but  a  slightly 
bitter  and  nauseous  taste  ;  is  insoluble  in  cold  water,  very  sparingly 
soluble  in  hot,  and  slightly  so  in  alcohol  ;  acts  faintly  on  turmeric, 
but  unites  with  acids  and  forms  neutral  salts,  which,  however,  are 
mostly  uncrystallizable.  —  Jour,  de  Phar.  vii.  and  viii.  Nagcndics 
Form.  79. 

According  to  Magendie  this  alkali,  like  opium,  may  produce  vomit- 
ing and  sleep,  but  its  emetic  powers  seem  to  be  more  decided,  while 
its  narcotic  properties  are  less  so  than  those  of  opium. 

Vinline. — A  vegetable  alkali,  thought  to  exist  in  the  Viola  odorata' 
It  has  properties  analogous  to  emetine  and  may  be  extracted  from  the 
root,  leaves,  flowers  arid  seeds  of  the  plant.— Jour,  of  P liar.  Jan.  1824. 
Urc's  Dictionary. 

Substances  somewhat  allied  to  the  preceding^  but  not  alkaline* 

Amygdatin. — A  substance  extracted  in  1830  by  Robiquet  and  Bou* 
tron— Charlard  from  the  bitter  almond. — Ann.  de  Cltim.  tt  de  Pnys* 
xliv.  352. 

Asparagin. — Discovered  by  MM.  Vauquelin  and  Robiquet,  in  the 
juice  of  the  asparagus.  It  is  deposited  by  evaporation  in  crystals, 
having  the  form  of  a  rectangular  octahedron,  six-sided  prism  or  right 
rhombic  prism  ;  has  a  cool  and  slightly  nauseous  taste  ;  is  soluble  in 
water,  and  has  neither  an  acid  nor  alkaline  reaction. — Ann.  de  (.him* 
Ivii.  88. 

Bafisnrin  was  first  noticed  in  gum  bassnra  by  Vauquelin.  Accord- 
ing to  Gehlen  arid  Bucholz.  it  is  contained,  together  with  common 
gum,  in  the  gum  tragacanth  ;  and  John  found  it  in  the  gum  of  the 
cherry  tree.  Salep,  from  the  experiments  of  Caventou,  appears  to 
consist  almost  totally  of  bassorin.  It  is  characterized  by  forming  with 
cold  water  a  bulky  jelly,  which  is  insoluble  in  that  menstruum,  a» 
weil  as  in  alcohol  and  ether;  is  not  soluble  in  boiling  water,  except 
by  long  continued  ebullition,  when  the  bassorin  at  length  disappears, 
and  is  converted  into  a  substance  similar  to  gum  arabic. 

Ccffcin  was  discovered  in  coffoe  by  M.  Robiquet  in  1821,  and  wa* 


VEGETABLE    SUBSTANCES.  385 

soon  after  obtained  from  the  same  source  by  Pelletier  and  Caventou, 
without  a  knowledge  of  the  discovery  of  Robiquet  It  is  a  white  crys- 
talline volatile  matter,  which  is  soluble  in  boiling  water  and  alcohol, 
and  is  deposited,  on  cooling,  in  the  form  of  silky  filaments,  like  amian- 
thus. It  does  not  affect  the  vegetable  blue  colours,  nor  combine  with 
acids. — Jour.  de  Phar.for  May,  18*26. 

Catkardn. — The  name  has  been  applied  by  MM.  Lassaigne  and 
Feneulle  to  the  active  principle  of  senna.  It  is  uncrystallizable,  of 
a  bitter  nauseous  taste,  reddish  yellow  colour,  and  soluble  in  water 
and  alcohol.—  Jinn,  de  Chirn  et  de  Phys.  xvi. 

Cklorophyle.  —  k.  name  applied  by  Pelletier  and  Caventou  to  the  green 
colouring  matter  of  leaves.  It  is  prepared  by  bruising  green  leaves  in- 
to a  pulp  with  water,  pressing  out  all  the  liquid  and  boiling  the  pulp  in 
alcohol.  The  solution  is  mixed  with  water,  and  the  spirit  driven  off 
by  distillation,  when  the  chlorophyle  is  left  floating  on  the  water. 

Colocyntin. — This  name  is  applied  by  Vauquelin  to  a  bitter  re^inoui 
matter  extracted  from  colocynth,  and  to  which  he  ascribes  the  proper- 
ties of  this  substance.  —  Brandes  Jour,  xviii.  400. 

Columbin.—  Obtained  from  the  Columbo  root  by  M.  Wittstock.  It 
occurs  in  colourless  prismatic  crystals  ;  is  extremely  bitter,  inodorous, 
and  without  effect  on  vegetable  colours  ;  is  soluble  in  about  30  or 
40  parts  of  boiling  alcohol,  less  so  in  cold  alcohol,  ether  and  water, 
yet  the  solutions  are  intensely  bitter  ;  is  decomposed  by  nitric,  sul- 
phuric arid  muriatic  acids,  as  well  as  by  intense  heat,  without  evolu- 
tion of  ammonia.—  Jour,  of  the  Royal  Institution,  ii.  631. 

Condn.  the  active  principle  of  the  Conium  w^cuhitum,  L.,  extract- 
ed by  MM.  Brandes  and  Geiseke,  half  a  grain  of  which  is  said  to  hav« 
proved  fatal  to  a  rabbit,  the  symptoms  being  the  same  as  those  produc- 
ed by  strychnine. —  Brand.es  Jour.  JV.  £.  iii.  227. 

Cytisin. — A  bitter  purgative  extractive  matter  similar  to  cathartin, 
found  by  Lassaigne  and  Chevalier  in  the  Cytisus  alpinus. 

Dahlin  is  found  in  the  Dahlia,  or  Georgia  of  botanists,  and  in  the 
Hduintlms  tuherosus,  L.  or  Jerusalem  artichoke.  It  is  a  white  pul- 
rerulent  substance,  more  soluble  in  hot  than  in  cold  water,  arid  inso- 
luble in  alcohol  ;  appears  to  have  most  analogy  with  starch  and  inulin. 
—  Ijttyen,,  Ann.  de  Chun,  et  de  ljhys.  xxiv  209.  Henry,  ii.  353. 

Dracin. — A  principle  obtained  from  the  gummi-resinous  substance 
called  Drngon's  Blood,  which  has  a  slight  affinity  to  the  vegetable  al- 
kalies. —  Melandri,  in  Phil.  Mug.  and  Ann.  ii  394.  Henry,  ii.  363. 

Fungin. — This  name  is  applied  by  M.  Braconnot  to  the  fleshy  sub- 
stance of  the  mushroom.  It  is  procured  in  a  pure  state  by  digestion 
in  hot  water,  to  which  a  little  alkali  is  added  ;  is  nutritious  in  a  high 
degree,  and  in  composition  is  very  analogous  to  animal  substances  ; 
like  (lesh,  it  yields  nitrogen  gas  when  digested  in  dilute  nitric  acid. 

Gentianin  — Obtained  from  the  Geniiana  lutea  or  gentian,  about  the 
game  time,  by  M.  Henry  and  M.  Caventou.  It  is  yellow,  inodorous, 
possessing  strongly  the  aromatic  bitterness  of  the  gentian,  more  de- 
cidedly so  however,  when  it  is  dissolved  in  an  acid  ;  it  is  highly  solu- 
ble in  ether  and  alcohol,  from  which  it  may  be  separated  in  the  form 
of  very  small,  yellow,  needle-like  crystals  :  does  not  sensibly  change 
the  colour  of  litmus  when  blue,  or  when  reddened  by  acids,  being  ap- 
parently neutral ;  it  does  not  possess  any  poisonous  qualities.  —  Ma~ 
gendies  Formulary,  83. 


386          VEGETABLE  SUBSTANCES. 

Hematin. — The  colouring  principle  of  the  H&mntoxylon  campcrkian- 
um,  or  logwood.  It  occurs  in  small  brilliant  crystals,  of  a  reddish- white 
colour,  and  slightly  bitter,  astringent  and  acrid  taste  ;  soluble  in  boil- 
ing water,  to  which  it  gives  an  orange  red  colour.  —  Chcvreul,  Jinn,  de 
Ckirn.  Ixxxi.  129.  Brundes  Jour.  xx.  389. 

Imperatorin. — A  crystalline  principle  resembling  piperin,  discovered 
by  Osann  in  the  root  of  the  Impcraloria  Ostruthium. 

Jtiulin  is  a  white  powder  like  starch,  which  is  spontaneously  deposit- 
ed from  a  decoction  of  the  roots  of  the  Imila  htlenium  or  elecampane; 
is  insoluble  in  cold,  and  soluble  in  hot  water,  and  is  deposited  from 
the  latter  as  it  cools,  a  character  which  distinguishes  it  from  starch. 
With  iodine  it  forms  a  greenish-yellow  compound  of  a  perishable  na- 
ture. Its  solution  is  somewhat  mucilaginous;  but  inulin  is  distin- 
guished from  gum  by  insolubility  in  cold  water,  and  in  not  yielding  the 
saccholactic  acid  when  digested  in  nitric  acid. 

Legumin  is  exti acted  from  the  pulp  of  ripe  peas,  by  steeping  in  hot 
water.  It  is  white,  and  when  dried  semi-transparent  ;  forms  a  mucil- 
age with  tartaric  acid  ;  soluble  in  all  alkalies  and  their  carbonates. — 
Einhof,  in  Ann.  de  Chirn  et  de  Phys.  xxiv.  209.  Henry,  ii.  353. 

Liriodendrin  —Discovered  in  the  bark  of  the  Liriodendron  tulipi- 
fera,  or  American  tulip-tree,  by  Professor  J.  P.  Emmet,  of  Virginia. 

When  obtained  from  the  alcoholic  solution  by  spontaneous  evapora- 
tion, it  crystallizes  in  triangular  and  rhomboidal  plates,  interspersed 
with  plumose  or  stellated  prisms  ;  some  are  perfectly  limpid,  others 
have  the  micaceous  appearance  of  boracic  acid  ;  in  this  state  it  freely 
dissolves  in  alcohol;  when  gently  heated  the  crystals  fuse,  slightly 
effervesce  (owing  to  the  escape  of  water,)  and  then  become  olive  co- 
loured, without  any  appearance  of  crystallization  on  cooling;  in  the 
fused  state  the  alcoholic  solution  is  always  olive  green,  and  scarcely 
gives  any  indication  of  a  regularly  formed  deposition,  unless  the  al- 
cohol employed  is  dilute. 

The  alcoholic  solutions  of  both  varieties  possess  an  intensely  bitter 
taste,  but  always  leave  the  impression  of  heat  upon  the  tongue. 

The  crystallized  substance  is  solid,  brittle  and  inodorous  at  40°,  fu- 
sible at  180-\  and  volatile  at  270°  F. ;  it  is  not  acted  on  by  weak  acid 
or  alkaline  solutions,  but  is  dissolved  by  concentrated  sulphuric  and  ni- 
tric acid.  According  to  Dr.  Emmet,  the  properties  of  this  substance 
appear  to  place  it  with  camphor  as  a  connecting  link  between  the  re- 
sins and  volatile  oils.—  Journal  of  the.  Pliilftdtlphia  College  of  Phar- 
macy. 

Lupnlin.—A  name  given  by  Dr.  Ansel  W.  Ives.  to  the  active  princi- 
ple of  the  Hnmulns  lupiiltts,  or  common  hop.  It  is  contained  in  all 
parts  of  the  plant,  but  chiefly  in  the  female  flowers. — Silliman's  Jour. 
ii.  302. 

Madrtrin. — An  extractive  matter  obtained  by  Dr.  Duncan  from  the 
Ca  lop  I  ris  Madari  i . 

M&  Jut  fin. — This  name  was  applied  by  John  to  the  pith  of  the  sun- 
flower, but  its  existence  as  an  independent  principle  is  somewhat  du- 
bious. The  term  pnllenin  has  been  given  by  the  same  chemist  to  the 
pollen  of  tulips. — Ann.  of  Phil.  vii.  49. 

Olimle. — When  the  gum  of  the  olive  tree  is  dissolved  in  alcohol,  and 
the  solution  is  allowed  to  evaporate  spontaneously,  a  peculiar  sab- 
itance,  apparently  different  from  the  other  proximate  principles  hith- 


VEGETABLE  SUBSTANCES.          337 

erto  examined,  is  deposited  either  in  flattened  needles  or  as  a  brilliant 
amylaceous  powder.  To  this  M.  Pelletier,  its  discoverer,  has  given 
the  name  of  Olivile. — Ann.  of  Phil.  xii. 

Paraffin  and  Eupion. — Two  substances  discovered  by  Reichenbach, 
in  the  products  of  the  distillation  of  vegetable  and  animal  substances. 

Picrotoxin  —Obtained  by  M.  Boullay  from  the  fruit  of  the  Cocculus 
suberosus  and  C.  Plukenetti  of  Decandolle.  It  occurs  in  four-sided  prisms, 
of  a  silky  lustre  ;  it  is  inodorous  but  very  bitter  ;  has  no  alkaline  re- 
action, nor  does  it  neutralize  acidity  ;  it  combines,  however,  with 
acids,  and  with  the  acetic  and  nitric  acids  forms  crystallizable  com- 
pounds.— See  M.  Casaseca,  in  the  Edm.  Jour,  of  Science,  v.  184,  who 
xhoics  that  this  canaot  be  ranked  among  the  alkalies. 

Piperin  is  the  name  which  is  applied  to  a  white  crystalline  substance 
extracted  from  black  pepper.  It  is  tasteless,  and  is  quite  free  from 
pungency,  the  stimulating  property  of  the  pepper  being  found  to  re- 
side in  a  fixed  oil.  [Pelletier,  in  Ann.  de  Chim.  et  de  Phijs.  xvi.  Car- 
penter, Sill.  Jour.  xiii.  334.]  Dr.  A.  T.  Thomson  has  extracted  it  from 
chamomile  flowers. — Turner. 

Plumhagin,  extracted  by  Dulong  from  the  root  of  the  Plumbago  Eu- 
ropcta,  is  soluble  in  water,  alcohol  and  ether,  and  crystallizes  from  its 
solutions  in  acicular  crystals  of  a  yellow  colour.  Its  aqueous  solution 
is  made  cherry  red  by  alkalies,  subacetate  of  lead,  and  per-muriate  of 
iron  ;  but  acids  restore  the  yellow  tint,  and  the  plumbagin  is  found  un- 
altered. Its  taste  is  at  first  sweet,  but  is  subsequently  sharp  and  acrid, 
extending  to  the  throat. — Brandes  Jour.  N.  S.  vi.  191. 

Polychroitc — The  colouring  matter  of  the  saffron.  It  is  of  a  deep 
yellow  colour,  deliquescent,  readily  soluble  in  water,  but  insoluble  in 
pure  sulphuric  ether. — Henry,  ii.  357. 

M.  Henry  of  Paris,  attributes  any  medicinal  activity  of  saffron  to  a 
volatile  oil  combined  with  the  colouring  matter. 

Populin — A  substance  found  by  Braconnot  in  the  bark  of  the  Popu- 
lus  trcmula,  analogous  in  properties  and  composition  to  Salicin,  if  not 
identical  with  it. 

Rhubarbarin  is  the  name  employed  by  Pfaff  to  designate  the  princi- 
ple in  which  the  purgative  property  of  the  rhubarb  resides.  M.  Nani 
of  Milan,  regards  the  active  principle  of  this  plant  as  a  vegetable  al- 
kali ;  but  he  has  not  given  any  proof  of  its  alkaline  nature. — Brande's 
Jour.  xvi.  172. 

Salicin. — A  peculiar  compound  obtained  by  M.  Leroux  from  the  bark 
of  the  Salix  alba,  L.  or  white  willow.  It  is  a  perfectly  white  body 
which  crystallizes  in  acicular  prisms  ;  has  a  very  bitter  taste  ;  is  solu- 
l)le  in  about  '20  parts  of  water  at  6(P,  more  soluble  in  hot,  and  to  al- 
most any  extent  in  boiling  water  ;  is  soluble  also  in  alcohol,  but  not 
in  ether,  nor  in  any  of  the  essential  oils,  except,  perhaps,  the  oil  of 
turpentine  ;  when  treated  with  sulphuric  acid  it  assumes  a  fine  red 
colour,  perfectly  resembling  bichromate  of  potassa;  with  nitric  acid 
it  forms  colourless  solutions. — Pelouze  and  J.  Gay  Lussac,  in  Phil.  Mag. 
and  Ann.  viii.  303. 

From  the  trials  which  have  been  made  with  this  substance  in  France, 
it  appears  to  possess  febrifuge  powers  scarcely  inferior  to  those  of  the 
sulphate  of  quinine. 

Gay  Lussac  and  Magendie,  who  were  appointed  by  the  Academy  of 
Sciences  to  examine  the  memoir  of  Leroux,  conclude  their  report  by 


388  VEGETABLE    SUBSTANCES. 

stating,  that  this  discovery  is,  without  contradiction,  one  of  the  most 
important  that  has  been  made  for  many  years  in  pharmacentical  chem- 
istry.— Ann  de  Chim.  xliii.  440,  or  Jour,  of  the  Royal  Institution,  i.  178. 

Sarcocoll  is  the  concrete  juice  of  the  Penctn  sarcocotta,  a  plant  which 
grows  in  the  northern  parts  of  Africa.  It  is  imported  in  the  form  of 
small  grains  of  a  yellowish  or  reddish  colour  like  gum  arabic,  to  which 
its  properties  are  similar.  It  has  a  sweetish  taste,  dissolves  in  the 
mouth  like  gum,  and  forms  a  mucilage  with  water.  It  is  distinguish- 
ed from  gum  by  its  solubility  in  alcohol,  and  by  its  aqueous  solution 
being  precipitated  by  tannin. — See  Thomson  s  Chemistry. 

ScMitin. — A  crystalline  principle  discovered  by  Vogel  in  the  Scilla 
maritima. 

Suberin. — This  name  has  been  applied  by  M.  Chevreul  to  the  cel- 
lular tissue  of  the  common  cork,  the  outer  bark  of  the  cork-oak,  (Qutr- 
cus  suber,)  after  the  astringent,  oily,  resinous,  and  other  soluble  mat- 
ters have  been  removed  by  the  action  of  water  and  alcohol.  Suberin 
differs  from  all  other  vegetable  principles  by  yielding  the  suberic  acid 
when  treated  by  nitric  acid. 

Tiglin. — The  active  principle  of  Croton-tigllum — soluble  in  alco- 
hol.— Brandes  Jour.  xx.  331. 

Ulmin — See  Ulmic  Acid,  p.  377. 

Zanihropicritc — Extracted  from  the  bark  of  a  species  of  Zanthoxi- 
lum.  It  forms  groups  of  greenish-yellow  crystals,  in  silky  divergent 
needles  ;  soluble  in  water  and  in  alcohol,  but  not  in  ether ;  it  is  dis- 
tinguished by  the  circumstance,  that  solution  of  gold  gives  with  it  a 
precipitate  which  is  quite  insoluble  in  alcohol  and  in  liquid  ammonia. 
—  Chevftllier  and  Pclleticr,  in  jinn,  de  Chim.  et  de  Phys.  Feb.  1827. — 
Henry,  ii.  362. 

Bitter  Principle — This  name  was  formerly  applied  to  a  substance  sup- 
posed to  be  common  to  bitter  plants,  and  to  be  the  cause  of  their  pe- 
culiar taste.  The  recent  discoveries  in  vegetable  chemistry,  however, 
have  shown  that  it  can  no  longer  be  regarded  as  a  uniform  unvarying 
principle.  The  bitterness  of  the  nux  vomica,  for  example,  is  owing  to 
strychnine,  that  of  opium  to  morphine,  that  of  cinchona  bark  to  cin- 
chonine  and  quinine,  &c.  The  cause  of  the  bitter  taste  in  the  root  of 
the  squill  is  different  from  that  of  the  hop  or  of  gentian.  The  term 
bitter  principle,  when  applied  to  any  one  principle  common  to  bitter 
plants,  conveys  an  erroneous  idea,  and  should  therefore  be  abandoned. 
Turner. 

Extractive  Matter.  —  This  expression,  if  applied  to  one  determinate 
principle  supposed  to  be  the  same  in  different  plants,  is  not  less  vague 
than  the  foregoing.  It  is  indeed  true  that  most  plants  yield  to  water 
a  substance  which  differs  from  gum,  sugar,  or  any  proximate  principle 
of  vegetables,  which,  therefore,  constitutes  a  part  of  what  is  called  an 
extract  in  pharmacy,  and  which,  for  want  of  a  more  precise  term,  may 
be  expressed  by  the  name  of  retractive.  It  must  be  remembered,  how- 
ever, that  this  matter  is  always  mixed  with  other  proximate  principles, 
and  that  there  is  no  proof  whatever  of  its  being  identical  in  different 
plants.  The  solution  of  saffron  in  hot  water,  said  to  afford  pure  ex 
tractive  matter  by  evaporation,  contains  the  colouring  matter  of  the 
plant,  together  with  all  the  other  vegetable  principles  of  saffron,  which 
happen  to  be  soluble  in  the  menstrum  employed. — Turner. 


VEGETABLE   SUBSTANCES.  389 

SECTION  III. 

SUBSTANCES  WHICH,  IN  RELATION  TO  OXYGEN,  CONTAIN  AN  EX- 
CESS OF  HYDROGEN. 

Oils. 

Oils  are  characterised  by  a  peculiar  unctuous  feel,  by  inflammabili- 
ty, and  by  insolubility  in  water.  They  are  divided  into  the  fixer'  and 
volatile  oils,  the  former  of  which  are  comparatively  fixed  in  the  fire, 
and,  therefore,  give  a  permanently  greasy  stain  to  paper  ;  while  the 
latt-r,  owing  to  their  volatility,  produce  a  stain  which  disappears  by 
gentle  heat. 

Fixed  Oils. — The  fixed  oils  are  usually  contained  in  the  seeds  of 
plants,  as  for  example,  in  the  almond,  linseed,  rapeseed,  and  poppy 
seed  ;  but  olive  oil  is  extracted  from  the  pulp  which  surrounds  the 
stone.  They  are  procured  by  bruising  the  seed,  and  subjecting  the 
pulpy  matter  to  pressure  in  hempen  bags,  a  gentle  heat  being  gene- 
rally employed  at  the  same  time  to  render  the  oil  more  limpid. 

Fixed  oils,  the  palm  oil  excepted,  are  fluid  at  common  temperatures, 
are  nearly  inodorous,  and  have  little  taste;  are  lighter  than  water, 
their  density  in  general  varying  from  0*9  to  0-96  ;  they  are  mostly  of 
a  yellow  colour,  and  can  be  rendered  nearly  or  quite  colourless,  by 
animal  charcoal  ;  boil  at  or  near  600 ^  F.  suffering  partial  decomposi- 
tion at  the  same  time,  an  inflammable  vapour  being  disengaged  even 
below  500  ^ ;  they  burn  in  the  open  air  with  a  clear  white  light,  and 
are  hence  employed  for  the  purpose  of  artificial  illumination.  By  ex- 
posure to  the  air,  these  oils  become  rancid,  in  consequence  of  the  acid- 
ification of  the  mucilaginous  matters  which  they  contain  ;  they  grad- 
ually also  lose  their  limpidity,  and  some  of  them,  called  on  this  ac- 
count drying  oils,  become  so  dry  that  they  no  longer  feel  unctuous  to 
the  touch,  nor  give  a  stain  to  paper.  This  property,  for  which  linseed 
oil  is  remarkable,  may  be  communicated  quickly  by  heating  the  oil  in 
an  open  vessel.  The  drying  oils  are  employed  for  making  oil  paint, 
and  mixed  with  lampblack  constitute  printer's  ink. 

Fixed  oils  do  not  unite  with  water,  but  by  the  aid  of  sugar  or  mu- 
cilage may  be  suspended  in  it,  so  as  to  constitute  an  emulsion;  they 
are  sparingly  soluble  in  alcohol  and  ether  ;  are  thickened  by  sulphuric 
acid,  and  also  by  chlorine  ;  are  acted  on  with  great  energy  by  nitric 
acid,  giving  rise,  in  some  instances,  to  the  production  of  flame; 
they  unite  also  with  the  common  metallic  oxides,  forming  varnishes  and 
plasters  ;  they  are  readily  attacked  by  alkalies,  with  ammonia,  forming 
a  soapy  liquid  called  rolutile  /inament,  with  the  fixed  alkalies,  soap,  the 
inferior  kind  being  made  with  potassa,  and  the  hard  with  soda. 

The  fixed  oils  and  fats  are  not  pure  proximate  principles,  but  consist 
of  two  substances,  called  by  Chevreul,  Stearine  and  Elaine;  the  for- 
mer of  which  is  solid,  and  abounds  in  suet,  butter  and  lard  ;  the  latter 
is  fluid,  and  is  found  in  greater  quantity  in  oils.  These  substances, 
however,  entirely  disappear  in  the  formation  of  soap,  being  converted 
into  three  compounds,  to  which  M.  Chevreul  has  applied  the  names  of 
Margaric  and  Oleic  acids,  and  Glycerine.  The  two  acids  enter  into 
combination  with  the  alkali  employed,  and  the  resulting  compound  IB 
soap.  A  similar  change  appears  to  be  effected  by  the  action  not  cnlj 
of  the  alkaline  earths,  but  of  several  of  the  other  metallic  oxides. 


390          VEGETABLE  SUBSTANCES. 

Soap  is  decomposed  by  acids,  and  by  earthy  and  most  metallic  salts. 
On  mixing  muriate  of  lime  with  a  solution  of  soap,  a  muriate  of  the 
alkali  is  produced,  and  the  lime  forms  an  insoluble  compound  with  the 
margaric  and  oleic  acids.  A  similar  change  ensues  when  a  salt  of  lead 
is  employed. 

From  the  analysis  of  Gay  Lussac  and  Thenard  it  is  probable  that 
olive  oil  consists  of  1  Ox.  8-f  11  Hyd.  11+10  Car.  60=79. 

REFERENCES.  The  Memoirs  of  AI.  Chevreul  are  published  in  the  Ann.  de 
Ckim.  et  de  Phys.  of  which  the  reader  will  fin.d  an  abstract  in  Vre^s  Client. 
Diet.  4ih  e.d.  articles  Elain  and  Fat.  Lewis1  Philosophical  Commerce  of  the 
Arts,  contains  a  history  of  Pt inters  Ink.  On  Soap,  see  Aikiifs  Chem.  Diet. 
Berzeliaa  in  his  Trai.  e  de  Chim,  gives  a  very  elaborate  account  of  the  fixed 
and  volatile  oils. 

Volatile  or  Essential  Oik. — These  substances,  to  which  aromatic 
plants  owe  their  flavour,  have  a  penetrating  odour  and  acrid  taste;  are 
soluble  in  alcohol,  though  in  different  proportions  ;  scarcely  soluble  in 
water  ;  they  are  volatilized  at  a  heat  below  212°  F.  by  which  they 
may  be  distinguished  from  the  fixed  oils  ;  they  burn  in  the  open  air 
with  a  clear  white  light ;  are  acted  upon  by  strong  nitric  acid,  with  the 
evolution  of  light  and  heat ;  do  not  readily  combine  with  alkalies  or 
metallic  oxides,  but  dissolve  sulphur  and  phosphorus. 

The  most  interesting  of  the  essential  oils  are  those  of  turpentine, 
caraway,  cloves,  peppermint,  nutmeg,  anise,  lavender,  cinnamon, 
citron,  and  charnornile-  Of  these  the  most  important  is  the  first, 
which  is  much  employed  in  the  preparation  of  varnishes,  and  for  some 
medical  and  chemical  purposes.  It  is  procured  by  distilling  common 
turpentine  ;  and  when  purified  by  a  second  distillation,  it  is  spirit  or 
essence  of  turpentine.  This  oil  cannot,  without  great  difficulty,  be  dis- 
solved in  alcohol,  though  turpentine  itself  is  easily  soluble  in  that 
fluid.  One  part  of  the  oil  may  be  dissolved  in  seven  parts  of  alcohol  ; 
but  on  standing  awhile  the  greatest  part  of  the  oil  separates  and  falls 
to  the  bottom.  [6f/-e.]  This  compound  gives  a  luminous  flame  when 
burned,  and  has  been  proposed  as  a  substitute  for  oil  and  gas  in  artifi- 
cial illumination.  The  purified  oil,  according  to  M.  H.  Labillardiere, 
contains  no  oxygen,  but  is  composed  of  carbon  and  hydrogen  in  such 
proportions,  that  one  volume  of  its  vapour  contains  four  volumes  of 
olefiant  gas,  and  two  volumes  of  the  vapour  of  carbon.— Journal  de, 
Pharmacie,  iv.  For  l/ie  anaiyxis  of  some  oils,  hy  Dr.  Ure  and  several 
olhtr  chemists,  see  his  Dictionary ,  4th  ed  Art  Oil. 

Camphor. — An  inflammable  substance,  closely  allied  to  the  essen- 
tial oils,  existing  ready  formed  in  the  Laurvs  Cawphora,  L.  of  Japan, 
and  in  several  other  plants.  It  has  a  bitterish,  aromatic,  pungent  taste, 
accompanied  with  a  sense  of  coolness  ;  it  is  unctuous  to  the  touch 
and  brittle,  and  may  be  easily  reduced  to  powder  by  trituration  with 
a  few  drops  of  alcohol  ;  its  specific  gravity  is  0-988  ;  is  very  volatile, 
fuses  at  288°  and  boils  at  400  F.;  it  is  insoluble  in  water,  but  freely 
soluble  in  alcohol,  from  which  it  is  thrown  down  by  water  ;  is  solu- 
ble also  in  the  fixed  and  volatile  oiis,  and  in  strong  acetic  acid  ;  is 
converted  by  sulphuric  acid  into  a  substance  resembling  tannin,  by 
nitric  acid,  into  camphoric  acid. 

According  to  Dr.  Ure  i  consists  of  1  Ox.  8-f-9  Hyd.  9-f  10  Car.  60 
=77.  Ure,  Chem.  Diet.  Jrt.  Camphor. 

Coumarin — A  name  applied  to  the  odoriferous  principle  of  the  Ton- 
ka bean,  which  is  the  produce  of  the  D  plcryx  odorata,  fVilltl.  It  is 


VEGETABLE  SUBSTANCES.         391 

white,  of  a  hot  pungent  taste,  and  distinct  aromatic  odour  ;  it  crystal- 
lizes in  four  sided  prisms  ;  is  moderately  hard,  and  is  heavier  than 
water  ;  is  sparingly  soluble  in  water,  but  readily  so  in  ether,  alcohol, 
the  fixed  and  volatile  oils. 

This  substance  appears  to  be  nearly  allied  to  the  essential  oils.  — 
Boullay  and  Boutron-  Charlard,  in  Jour,  de  Phar.  for  1825.  Turner. 

Resins. 

Resins  are  the  inspissated  juices  of  plants,  and  commonly  occur 
either  pure  or  in  combination  with  an  essential  oil.  They  are  solid 
at  common  temperatures,  brittle,  inodorous,  and  insipid;  are  non- 
conductors of  electricity,  and  when  rubbed  become  negatively  elec- 
tric ;  they  are  generally  of  a  yellow  colour,  and  semi-transparent  ; 
are  fused  by  heat,  and  at  a  still  higher  temperature  are  decomposed  ; 
are  soluble  in  alcohol,  ether,  and  the  essential  oils,  and,  from  the  for- 
mer, they  are  precipitated  by  water,  in  which  they  are  quite  insoluble  ; 
they  are  soluble  also  in  pure  potassa  and  soda,  and  are  decomposed 
by  the  acids,  the  nitric  forming  with  them  a  kind  of  tannin. 

The  most  important  of  these  substances  are  common  resin,  or  rosin, 
copal,  lac,  sandarach.  mastich,  elemi  and  dragon's  blood. 

Resins  are  the  bases  of  varnishes,  and  melted  with  wax  and  oil  con- 
stitute ointments  and  plasters.  Sealing  wax  is  composed  of  lac,  Ven- 
ice turpentine  and  common  resin. 

The  resins  and  gurn  resins  have  been  much  investigated  and  with 
great  success  by  Unverdorben.  In  a  series  of  very  elaborate  memoirs 
he  has  shown  that  many  of  the  known  resins  are  mixtures  of  several 
substances  of  the  same  class,  which  may  in  most  instances  be  separ- 
ated from  each  other  by  the  action  of  alcohol  and  ether.  And  he  has 
also  shown  that  all  the  resins  possess  the  power  of  forming  salts  with 
oxides  in  definite  proportions  and  are  therefore  analogous  to  the  acids. 

REFERENCES.  Thomson  on  common  Rosin,  in  Ann.  of  Phil.  xv.  4fi8. 
Hatchet?  s  able  investigations  of  the  properties  uf  the  Resins  will  be  found  in 
the  Phil.  Trans,  for  1804,  18;J5  and  18>;6.  lire's  Chem,  Diet.  Art.  Resin. 
Berzelius,  Traite  de  Chim.  v. 


r.  —  This  substance  is  found  plentifully  in  beds  of  bituminous 
wood  in  some  parts  of  Prussia.  It  is  undoubtedly  of  vegetable  origin, 
and  has  the  general  properties  of  a  resin,  but  is  distinguished  by  yield- 
ing succinic  acid,  when  heated  in  close  vessels.  —  For  details  concerning 
this  substance,  see  Ure's  Chem.  Diet. 

Balsams  —  The  balsams  are  native  compounds  of  resin  and  benzoic 
acid,  and  issue  from  incisions  made  in  the  trees  which  contain  them, 
in  the  same  manner  as  turpentine  from  the  fir.  Some  of  them,  such 
as  storax  and  benzoin,  are  solid  ;  while  others,  of  which  the  balsams 
of  Tolu  and  Peru  are  examples,  are  viscid  fluids. 

Gum-Resins.  —  The  substances  to  which  this  name  is  applied  are 
the  concrete  juices  of  certain  plants,  and  consist  of  resin,  essential 
oil,  gum,  and  extractive  vegetable  matter.  The  two  former  princi- 
ples are  soluble  in  alcohol,  and  the  two  latter  in  water.  Their  proper 
solvent,  therefore,  is  proof  spirit.  Under  the  class  of  gum-resins  are 
comprehended  several  valuable  medicines,  such  as  aloes,  ammonia- 
cum,  assafoBtida,  euphorbium,  galbanum,  gamboge,  myrrh,  scammo- 
ny  and  guaiacum.—  HatchelL  in  Phil.  Trans. 


392  VEGETABLE  SUBSTANCES. 

Caoutchouc,  commonly  called  elastic  gum,  or  Indian  rubber,  is  the 
concrete  juice  of  the  Siphonia  elastica,  Pers.  a  native  of  Brazil,  and 
of  several  East  India  trees,  as  the  FICUS  mdica,  &c.  The  most  re- 
markable property  of  this  substance  is  its  elasticity.  It  is  inflamma- 
ble, and  burns  with  a  bright  flame  ;  is  not  soluble  in  water,  but  rnay 
be  dissolved,  though  with  difficulty,  in  pure  ether ;  it  is  soluble  in  pe- 
troleum, cajeput  oil,  purified  naptha,  and  the  oil  of  sassafras  ;  it  loses 
its  elasticity  by  the  action  of  alkalies. 

This  substance  is  employed  for  forming  varnishes,  for  covering  cloth 
so  as  to  render  it  impervious  to  moisture,  &c. 

Dr.  J.  K.  Mitchell,  of  Philadelphia,  has  discovered  a  mode  of  mak- 
ing sheet-caoutchouc,  which  possesses  very  singular  properties. 

KEFERF.NCES.  /'or  a  notice  of  the  solubility  of  Caoutchouc  in  coal  nap~ 
tha,  see  Ann.  of  Phil.  xii.  Dr.  Mitchell's  discovery  is  described  in  the  Jour, 
nal  of  t':e  Phil.  College  of  Pharmacy,  for  J in.  1<>3<>,  and  in  a  note  to  Tur 
ner^s  Chem.by  Dr.  Bache  Faraday  on  pure  Caoutchouc,  and  the  substances 
by  which  it  is  accompanied  in  the  state  of  sap  or  juice  ^  Brande's  Jour.  xxi.  IT- 
Besides  Chemical  examinations,  this  paper  contains  a  list  of  the  most  i  ttpor* 
taut  memoirs  on  this  curious  substance.  Caoutchouc  found  in  Arkansas, 
Sill  Jour.  iii.  44. 

Wtx. — This  principle  exists  in  many  plants,  and  especially  in  the 
berries  of  the  Myrica  Cerifera,  L.  In  its  common  form  it  is  always 
more  or  les<  coloured,  but  when  pure  is  colourless  and  insipid  ;  its 
specific  gravity  is  0'96 .  it  is  solid  at  ordinary  temperatures,  and  some- 
what brittle,  but  rnay  be  easily  cut  with  a  knife,  when  it  exhibits  a  pe- 
culiar appearance,  called  the  waxy  lustre  ;  it  is  insoluble  in  water, 
sparingly  soluble  in  boiling  alcohol  and  ether  ;  it  is  readily  soluble  in 
the  fixed  oils  when  assisted  by  heat,  and  forms  a  compound  of  varia- 
ble consistence,  which  is  the  basis  of  cerates  and  ointments ;  it  melts  at 
about  150  '  F.  and  at  a  higher  temperature  it  is  converted  into  vapour  ; 
when  burned  in  contact  will1  air  it  yields  a  clear  white  light,  and  is 
hence  employed  for  forming  candles. 

According  to  Dr.  John,  wax  consists  of  two  portions,  one  of  which 
is  soluble  in  alcohol,  the  other  is  insoluble.  To  the  former  he  has 
given  the  name  of  Cerin,  and  to  the  latter  that  of  Myricin.  Accord- 
ing to  the  analysis  of  Dr.  Ure,  it  consists  of  1  O.  8-4-11  H.  114-13  C. 
78=97. 

REFKRENCES.  Ure's  Chem.  Die/.  Thenard,  Traite  de  Chim.  iv.  Dana's 
chtintc  I  examination  of  the  berries  of  Myrica  Cerifera,  Sil.  Joitr.  i.  294. 
Bran</S  s  analyst*  of  Vegetable  Wax  from  Brazil,  Phil  Trans.  Hill,  267. 
For  the  process  of  bleaching  wax,  see  AtkuSs  Cl.cm.  Diet.  art.  Wax. 

Alcohol— Atom.  Num.  23—Symb.  (2H+2C)+(O+H) 

This  principle  does  not  exist  ready  formed  in  plants,  but  is  the  pro- 
duct of  vinous  fermentation,  and  is  the  intoxicating  ingredient  of  all 
spirituous  arid  vinous  liquors. 

PROPERTIES.  Alcohol  is  considerably  lighter  than  water.  The 
lightest  that  can  be  obtained  by  simple  distillation  has  a  specific  gra- 
vity of  0.825,  but  by  the  intervention  of  substances  that  strongly  at- 
tract water,  it  has  been  brought  to  the  specific  gravity  of  0-796  at  60° 
F.  It  is  a  colourless  fluid,  of  a  penetrating  odour,  and  burning  taste ; 


VEGETABLE    SUBSTA1S7CES.  393 

is  highly  volatile,  boiling  when  its  density  is  0-820,  at  1763  F. ;  it  is 
highly  inflammable,  and  burns  with  a  yellowish  blue  flame,  the  colour 
of  which  varies  somewhat  with  the  stiength  of  the  alcohol,  and  it 
leaves  no  residuum,  being  converted  into  ca'bonic  acid  and  water ; 
it  is  remarkably  expansible  by  heat ;  at  50  F.  it  gives  a  gas,  the  den- 
sity of  which  is  to  that  of  the  atmosphere  as  1-613  is  to  1  .  it  unites  in 
all  proportions  with  water,  the  combination  being  usually  attended 
with  a  diminution  of  volume  and  an  increase  of  temperature ;  it  dis- 
solves few  of  the  salifiable  bases,  but  all  the  deliquescent  salts  are  so- 
luble in  it,  except  carbonate  of  potassa,  and  they  form  with  it  definite 
compounds,  analogous  to  the  hydrates,  which  have  been  called  Alco- 
ates ;  it  dissolves  also  many  vegetable  principles,  as  resins,  camphor, 
the  essential  oils,  &c  ;  and  it  has  never  been  congealed  by  any  known 
method  of  producing  artificial  cold. 

Congelation  of  Alcohol. — Common  spirits  freeze  in  severe  cold. — 
But  absolute  alcohol  did  not  congeal  when  it  was  exposed  by  Mr.  Wal- 
ker to  a  cold  of  —  90:i.  Professor  Leslie,  it  is  believed,  exposed  it  to 
a  cold  of  —  12CP  without  observing  any  congelation.  M.  hussy  of  Pa- 
ris succeeded  by  means  of  liquid  sulphurous  acid,  in  congealing  alco- 
hol of  sp.  gr.  0-85.  The  temperature  was  —  90°. — See  Thomson  on 
Heat,  Sfc.  171. 

PREPARATION,  &c.  Common  alcohol,  or  Spirit  of  Wine,*  is  pre- 
pared by  distilling  whiskey  or  some  ardent  spirit,  and  the  rectified 
spirit  of  wine  is  procured  bv  a  second  distillation.  The  first  has  a 
specific  gravity  of  about  0-867,  and  the  last  of  about  0-835  or  0-84. 
In  this  state  it  contains  a  quantity  of  water,  from  which  it  may  be 
freed  by  mixing  it  with  about  one-fourth  of  its  weight  of  dry  and 
warm  pearl-ash,  chloride  of  calcium,  or  some  other  substance  which 
has  a  strong  affinity  for  water,  arid  subsequent  distillation  at  a  low 
heat.  But  a  more  easy  and  elegant  process  for  concentrating  alcohol, 
is  that  of  placing  it  with  powdered  quicklime  under  the  receiver  of  an 
air-pump,  as  proposed  by  Mr.  Graham.  The  alcohol  obtained  by  the 
preceding  processes  is  called  Absolute,  on  the  supposition  of  its  be- 
ing quite  free  from  water. 

The  strength  of  alcohol  can  be  determined  by  its  specific  gravity, 
and  tables  are  constructed,  showing  the  specific  gravity  of  various 
mixtures  of  alcohol  and  water.  Equal  weights  of  absolute  alcohol 
and  water  constitute  Proof  Spirit,  the  density  of  which  is  0-917  ;  but 
the  proof  spirit  employed  by  the  colleges  for  tinctures,  has  a  specific 
gravity  of  0-930  or  0-935.  —  Turner. 

Jttcohol  in  Wine. — It  has  been  a  subject  of  some  controversy  among 
chemists  whether  alcohol  exists  ready  formed  in  wine  or  whether  it  is 
generated  by  the  heat  employed  in  the  distillation.  The  latter  opinion 
was  supported  by  Fabroni  ;  [Ann.  de  Chim.  xxx.  220,]  but  its  fallacy 
has  been  completely  exhibited  by  the  able  investigations  of  Mr.  Brande, 
and  Gay  Lussac. 

The  existence  of  alcohol  ready  formed  in  wines  and  other  fermented 
liquors,  is  evident  from  the  following  considerations. 

*  Spirit  of  Wine  was  known  to  Raymond  Sully  in  the  13th  century,  and  dis- 
(  nguished  by  him  by  the  names  of  or'  aquae,  vita  ardens,  and  argentum  vivum 
vege.'a>>i/e  lie  knew  the  method  of  re  dering  it  stronger  bv  an  admixture 
of  drv  carbonate  of  potash  and  of  p  <  paring  vegetable  mixtures  by  means  of 
it. — Thomson's  History  of  Chemistry. 


394         VEGETABLE  SUBSTANCES. 

1.  Alcohol.  It  can  be  obtained  from  wines  by  distillation  invacuo  at  the 
temperature  of  60°  F.,  which  precludes  the  idea  that  it  is  formed  by 
the  action  of  heat  upon  the  elements  existing  in  the  fermented  liquor. 
—  Gay  Lussac.     Thenard,  Traite  de  Ctiim.  iv.  336. 

2.  When  a  portion  of  wine  is  partly  distilled  off  and  the   distilled 
liquor  is  afterwards  added  to  the  residuum  in  the  retort,  the  specific 
gravity  of  the  mixture  is  precisely  the  same  as  that  of  the  wine  pre- 
vious to  distillation.     I  confirmed 'the  statement  of  Mr.  Brande  on  this 
point  in  the  case  of  three  kinds  of  wine.     Alcohol,  being  much  lighter 
than  wine,  if  it  was  formed  during  the  process  of  distillation   would 
have  the  effect  of  reducing  the  specific  gravity  when  added  to  the  resi- 
duum, which  is  never  the  case. 

3.  When  the  colouring  and  extractive  matters  in  the  wine  are  pre- 
cipitated by  sub  acetate  of  lead,  the  pure  alcohol  may  be  separated  by 
the  subsequent  addition  of  dry  sub-carbonate  of  potash,  in  the  same 
manner,  as  from  whiskey,  gin  and  brandy. — Brande. 

It  may,  therefore,  be  considered  as  satisfactorily  proved  that  alcohol 
exists,  as  such,  in  wines  and  other  fermented  liquors  ;  but  there  is  still 
much  doubt  whether  their  intoxicating  powers  are  not  materially  modi- 
fied by  the  acid  and  other  vegetable  matters  which  they  contain. 

I  have  recently  analyzed  several  varieties  of  wines  and  other  liquors, 
chiefly  for  the  purpose  of  ascertaining  the  amount  of  alcohol  which 
they  contain.  The  process  adopted  was  that  of  slow  and  careful 
distillation,  and  the  accurate  determination  of  the  specific  gravi- 
ty of  the  distilled  liquor.  In  the  following  table  of  my  results,  the 
kind  of  liquor  is  designated  and  the  proportion  of  alcohol  per  cent,  by 
measure  which  they  were  found  to  contain,  is  stated.  And  in  order 
that  the  strength  of  these  liquors  may  be  easily  compared  with  that  of 
those  examined  by  Mr.  Brande,  I  have  taken  as  the  standard,  alcohol 
of  the  specific  gravity  of  0-825  at  the  temperature  of  60J  F. 


VEGETABLE   SUBSTANCES. 


395 


TABLE  of  tlie  proportion  of  Alcohol  per  cent.  BY  MEASURE, 
contained  in  several  kinds  of  Wine  and  other  Liquors  ; — 
the  specific  gravity  of  the  standard  Alcohol  being  0.825  at 
the  temperature  of  (50°  F. 


Kind  of  Liquor. 

l5i 

-  ^7 
c  ~  £ 
~~  e 
£J5 

£'5  JO 

Kind  of  Liquor. 

r-H 

r  —  i» 

=•£  £ 

£^£ 

1.  Madeira  (common,) 
2.     Do.   (imported  from  the 
house  of  Robt.  Seal,) 
3.     Do.     (common,) 
4.     Do.   (imported  from  the 
house  of  H  oughton  &  Co. 
5.     Do.     ("  Farquhar,"    in 
bottle  40  years,) 
6.     Do.     (20  years  old,) 
7.     Do.     ("  Edgar,") 
S.     Do.     ("  Brammin,") 
9.     Do.     (common,) 
10.     Do.     (''Wanderer,") 
11.     Do.     ("Blackburn," 
old,) 
12.     Do.     (said  to  be  the  pure 
juice,  28  years  old,) 
13.  Sercial  Madeira, 
14.     Do,         Do. 

25.27 

23.11 
22.41 

22.25 

21.79 
21.45 
21.30 
20.91 

20.72 
20.70 

20.68 

19.30 
25.18 
18.96 

21.  Torres  Vedras, 
22.  Sauterne, 

20.51 
13.00 

23.  Claret,  (Chateau  Mar- 
geaux,) 
24.  Do.  (Palmer  Margeaux,) 

11.80 
11.04 

Average, 

11.42 

11.25 
10.57 

10.67 
7.38 

25.  American  Wine,  (2  years 
oldj 
26.  Metheglin,   20  years  in 
bottle, 

27.  Ale,  (Albany,  in  bottle  2 
years,  ) 
28.  Do.  (Albany,  in  barrel,) 

29.  Cider,  (in  bottle,) 
30.  Do.  (in  barrel,  6  months,  ) 
31.  Do.  (in  barrel,) 

4.80 
4.84 
4.41 

Average  of  14  kinds, 

21.75 

15.  London  Particular, 
16.  Bucellas, 
17.  Brown  Sherry, 

22.10 

18.80 
18.03 

Average, 

468 

32.  Irish  Whiskey,  (imported 
in  1825,) 
33.  Gin(genuine'  'Hollands'') 
34.  Brandy,  (common.) 
35.  Whiskey,    (common.) 
36.  Spirits  of  Wine,(obtained 
at  the  druggists,) 
37.        Do. 

\ 
73.70 
55.44 
51  01 
42.95 

93.27 
95.35 

18.  Port,  (7  years  in  bottle,) 
19.     Do. 
20.     Do. 

22.87 
22.35 
21.98 

Average, 

22.60 

The  results  in  the  above  table  agree  generally  with  those  of  Mr. 
Brande.  In  all  cases  where  the  difference  was  marked,  the  trials  were 
repeated  several  times,  and  the  mean  of  these  is  stated.  This  was  par- 
ticularly so  with  Nos.  13  &  14,  22,  23  &  24.  The  ale,  IN 6.  27,  con- 
tains more  alcohol  than  any  put  down  in  the  table  of  Mr.  Brande  as 
ordinarily  published  ;  but  in  the  Journal  of  Science  and  the  Arts, 
(Vol.  5,  p.  124)  he  states  that  Lincolnshire  Ale,  brewed  by  Sir  Joseph 
Banks,  contained  10-84  per  cent,  of  alcohol.  Our  cider  it  would  seem 
contains  less  alcohol  than  the  lowest  average  of  the  specimens  exam- 
ined by  Mr.  Brande,  which  is  5-21  per  cent. 


390  VEGETABLE    SUBSTANCES. 

REFERENCES.  For  a  table  of  /he  specific  gravities  of  Alcohol  of  different 
strength,  see  Henry's  Chem.  ii.  o73.  Graham  on  the  concentration  of  Alco- 
hol, inEdin.  Phil.  Trnn*.  1823.  On  th<<  concentration  of  Alcohol  tiy  blad- 
ders, Brande's  Jour,  xviii.  !80.  Graham  on  the  Alcoates,  Branded  Jour.  N. 
8.  iv.  44*2.  On  Alcohol  in  u-ines,  see  Thenard,  iv  — Chaptal  on  Wine,  mid 
Murray's  Chem.  For  Brandt's  table  of  the  quantity  of  Alcohol  in  various 
wines,  SfC.  see  his  Manual  of  Chemistry  or  Pharmacy.  The  experimental 
details  are  published  in  Phil.  Trans,  for  181 1  and  1813.  The  article  distilla- 
tion in  the  Supplement  to  the  EHCIJ.  Brittannica,  by  Dr.  Thomson.  Hender- 
son on  Wines. 

Ether. 

The  name  Elher  was  formerly  employed  to  designate  the  volatile 
inflammable  liquid  which  is  formed  by  heating  a  mixture  of  alcohol 
and  sulphuric  acid  ;  but  the  same  term  has  since  been  extended  to 
several  other  compounds  produced  by  the  action  of  acids  on  alcohol, 
and  which,  from  their  volatility  and  inflammability,  were  supposed  to 
be  identical  or  nearly  so  with  sulphuric  ether. 

M.  Boullay,  sen.,  divides  the  ethers  into  three  classes  ;  1st.  Those 
obtained  by  acting  upon  alcohol  with  sulphuric,  phosphoric  and  arse- 
nic acids,  which  are  identical  ;  2dly.  Those  produced  by  the  combi- 
nation of  hydro-carbon  with  certain  hydracids  ;  3dly.  Those  which, 
according  to  the  experiments  of  Thenard  and  of  Boullay,  are  constitu- 
ted of  alcohol  and  an  oxacid. 

Ethers  of  the  First   Class. 
Sulphuric  Ether.— Atom.  Num.  37—$i/mh.  2  (2H+2C)+(O+H.) 

A  colourless  fluid,  of  a  hot  pungent  taste,  and  fragrant  odour  ;  its 
specific  gravity  in  its  purest  form,  is  about  0*700,  and  according  to 
Lowitz,  0-632,  but  the  ether  of  the  shops  is  seldom  less  than  0*750, 
owing  to  the  presence  of  alcohol  ;  it  is  extremely  volatile,  a  few  drops 
poured  on  the  hand  evaporating  instantly  with  the  production  of  cold  ; 
when  of  the  specific  gravity  of  0  713,  it  boils  at  92Ct2  F.  under  the  pres- 
sure of  the  atmosphere,  [Du-mus  and  Boullny,]  and  in  racuo  at  20-  be- 
low 0  ;  at  46 J  below  zero  it  is  congealed  ;  its  vapour  has  a  density  of 
2-586  compared  to  air  as  I  ;  it.  combines  with  alcohol  in  all  proportions, 
but  not  with  water ;  it  is  highly  inflammable,  burning-  with  a  blue 
flame,  and  forming  carbonic  acid  arid  water  ;  and  with  oxygen  gas  its 
vapour  forms  an  explosive  mixture  ;  it  may  be  decomposed  by  being 
passed  through  a  red  hot  porcelain  tube  ;  it  dissolves  many  of  the  re- 
sins and  essential  oils,  and  some  of  the  vegetable  alkalies,  and  when 
breathed  produces  effects  similar  to  those  produced  by  nitrous  oxide  ', 
but  this  is  sometimes  attended  with  danger. — See  Brandes  Jour.  iv. 
159. 

Action  of  Water. — When  ether  is  agitated  with  that  fluid,  the  great- 
er part  separates  on  standing,  a  small  quantity  being  retained,  which 
imparts  an  ethereal  odour  to  the  water  ;  the  ether  so  washed  is  very 
pure,  because  the  water  retains  the  alcohol  with  which  it  is  mixed. 

Action  of  Platinum. — When  a  coil  of  platinum  wire  is  heated  to  red- 
ness, and  then  suspended  above  the  surface  of  ether  contained  in  an 


VEGETABLE  SUBSTANCES.          397 

open  vessel,  the  wire  instantly  begins  to  glow,  and  continues  in  that 
state  until  all  the  ether  is  consumed.  During  this  slow  combustion, 
pungent  acrid  fumes  are  emitted,  which  Mr.  Daniel  considered  as  a 
new  acid,  and  described  under  the  name  of  Lampic  Acid,-  but  he  has 
since  ascertained  that  its  acidity  is  owing  to  the  acetic  acid,  which  is 
combined  with  some  compound  of  carbon  and  hydrogen,  different  both 
from  ether  and  alcohol. — Brandes  Jour.  vi.  and  xii. 

If  platinum  sponge  be  heated  and  put  into  the  vapour  of  ether,  it 
becomes  red  hot,  and  continues  so  as  long  as  any  of  the  vapour  is  un- 
consumed  According  to  Dr.  Thomson,  powdered  black  oxide  of  man- 
ganese, oxide  of  nickel,  oxide  of  cobalt,  oxide  of  uranium,  oxide  of 
tin,  &c.  when  in  the  loose  and  porous  state  in  which  they  are  produced 
by  decomposing  the  oxalates  of  the  several  metals  by  heat  in  the  open 
air,  may  be  substituted  for  platinum. — Thomson  on  Heat,  tyc. 

Action  of  Light — If  ether  is  exposed  to  light  in  a  vessel  partially  fill- 
ed, and  which  is  frequently  opened,  it  gradually  absorbs  oxygen,  and  a 
portion  of  acetic  acid  is  generated.  This  change  was  first  noticed  by 
M.  Planche,  and  has  been  confirmed  by  Gay  Lussac.  M.  Henry,  of 
Paris,  attributes  its  developement  to  acetic  ether,  which  he  believes  to 
be  always  contained  in  sulphuric  ether. — Turner. 

PREPARATION.  Ether  may  be  made  by  mixing  gradually  equal 
parts  of  strong  sulphuric  acid  and  alcohol,  and  subjecting  the  mixture 
to  slow  distillation,  into  a  receiver  surrounded  by  ice,  by  a  carefully 
regulated  heat.  The  ether  which  first  passes  over  is  impure,  being 
contaminated  with  alcohol  and  with  sulphurous  acid.  To  separate 
these  impurities,  it  should  be  agitated  with  a  strong  solution  of  potas- 
sa,  which  neutralizes  the  acid,  while  the  water  unites  with  the  alco- 
hol. The  ether  is  then  distilled  by  a  very  gentle  heat,  and  may  be 
rendered  still  stronger  by  distillation  from  the  chloride  of  calcium. 

The  theory  of  the  formation  of  ether  will  be  understood,  when  it  is 
stated  that,  according  to  the  most  correct  analysis,  ether  is  supposed 
to  consist  of  two  proportions  of  olefiant  gas  and  one  proportion  of 
water.  Now,  alcohol  is  composed  of  one  proportion  of  olefiant  gas 
and  one  of  water  ;  so  that,  if  from  two  proportions  of  alcohol  one  of 
water  be  withdrawn,  the  remaining  elements  are  in  exact  proportion 
for  constituting  ether.  This  is  exactly  the  mode  in  which  sulphuric 
acid  is  supposed  to  operate  in  generating  ether,  an  effect  which  it  is 
well  calculated  to  produce,  owing  to  its  strong  affinity  for  moisture. 

Hence,  also,  when  a  larger  proportion  of  sulphuric  acid  is  added  to 
alcohol,  it  combines  with  the  whole  of  the  water,  and  pure  olefiant 
gas  is  evolved. 

Sulphovinic  Acid  is  a  peculiar  acid  formed  during  the  preceding 
process,  and  which,  according  to  Mr.  Hennel,  is  composed  of  sulphur- 
ic acid  and  carburet  of  hydrogen. — Phil.  Trans.  1826,  247,  or  Brande's 
Jour.  xxi.  331. 

Phosphoric  Ether  is  very  volatile  ;  boils  at  100°  F. ;  is  soluble  in 
eight  or  ten  parts  of  water,  and  burns  with  a  white  flame.  It  is  ob- 
tained by  distilling  a  mixture  of  thick  tenaceous  phosphoric  acid  and 
alcohol.—  Boullay,  Ann.  dc  Chim.  Ixii.  192. 

Ethers  of  the  Second  Class. 

Muriatic  Ether. — This  compound  is  highly  inflammable  and  volatil- 
izes still  more  rapidly  than  sulphuric  ether  ;  when  burned  it  gives  out 

AA 


398          VEGETABLE  SUBSTANCES. 

muriatic  acid  gas.     It  may  be  obtained  by  distilling  equal  measures  of 
alcohol  and  concentrated  muriatic  acid. 

Chloric  Ether,  Hydriodic  Ether,  Fluoric  Ether,  and  Fluoboric  Ether 
may  also  be  obtained  by  processes  analogous  to  those  already  describ- 
ed.— See  Henry's  Chern.  ii.  395. 

Ethers  of  the  Third  Class. 

Nitric  Ether. — This  substance  agrees  with  sulphuric  ether  in  its  lead- 
ing properties,  but  it  is  still  more  volatile ;  it  usually  reddens  litmus, 
and  though  this  property  may  be  destroyed  by  a  little  lime,  it  soon  be- 
comes acid  by  keeping  ;  it  is  highly  combustible  at  common  tempera- 
tures, and  under  ordinary  pressure  the  specific  gravity  of  its  vapour  is 
2*628.  It  is  prepared  by  distilling  a  mixture  of  concentrated  nitric 
acid  with  an  equal  weight  of  alcohol ;  but  the  process  requires  great 
care. 

Sweet  Spirits  of  Nitre,  is  a  solution  of  nitric  ether  in  alcohol.     When 

Sure  it  is  colourless,  possesses  a  peculiar  odour  and  a  specific  gravity  of 
•850.     It  reddens  litmus  feebly,  and  volatilizes  without  leaving  any 
residue.     The  presence  of  muriatic  and  sulphuric  acids  may  be  detect- 
ed by  diluting  it  with  a  sufficient  quantity  of  water,  and  adding  solu- 
tion of  nitrate  of  silver  and  chloride  of  barium. 

Acetic  Ether. — This  compound  is  volatile  ;  has  a  specific  gravity  of 
0*866,  being  heavier  than  most  other  ethers  ;  it  burns  with  a  yellow- 
ish-white flame,  and  during  its  combustion  acetic  acid  is  developed. — 
It  rs  formed  by  distilling  12  or  15  times  in  succession  concentrated 
acetic  acid  (procured  from  acetate  of  copper)  with  alcohol,  and  return- 
ing the  distilled  liquor  to  charge  the  retort. 

REFERENCES.  Thomson**  System  of  Chetn,.  Thenard,  Trailed  Chim.  \v, 
146.  Henry's  Chem.  ii.  383.  Brande's  Manual  of  Pharmacy.  DanieiL  on 
Lampic  Acid  and  the  Lampates.  Bran  tie's  Jour.  vi.  318.  Harems  description 
of  an  aparatus  for  preparing  Nitric  Ether ,  Sill.  Jour.  ii.  326.  Daltons  Me 
moir  on  Sulphuric  Ethtr,  Arm.  of  Phil.  \v.  117.  Thenard  on  the  action  of 
Vegetable  Acids  on  Alcohol,  Mem.  d1 Arcueil,  ii.  5,  or  Phil.  Mag.  xxxvii.  216. 
Dumas  and  Boullay,  Ann.  de  Chim.  et  de  Phys.  Jan.  13:28. 

Bituminous  Substances. 

Under  this  title  are  included  several  inflammable  substances,  which, 
though  of  vegetable  origin,  are  found  in  the  earth,  or  issue  from  its 
surface.  They  may  be  conveniently  arranged  under  the  two  heads  of 
bitumen  and  pit-coal.  The  first  comprehends  naphtha,  petroleum, 
mineral  tar,  mineral  pitch,  asphaltum,  and  retinasphaltum,  of  which 
the  three  first  mentioned  are  liquid,  and  the  others  solid.  The  second 
comprises  brown  coal,  the  different  varieties  of  common  or  black  coal, 
and  glance  coal. 

Bitumen — Naphtha. — A  volatile  limpid  liquid,  occurring  in  some  parts 
of  Italy,  and  on  the  banks  of  the  Caspian  sea  ;  and  produced  also  by 
distillation  from  petroleum.  It  has  a  strong  peculiar  odour,  and  light 
yellow  colour  ;  its  specific  gravity,  when  highly  rectified,  is  0-753  at 
61°  F.;  it  is  very  inflammable,  and  burns  with  a  white  flame  mixed 
with  much  smoke  ;  at  186°  F.  it  enters  into  ebullition,  and  its  vapour 
has  a  density  of  2-833 ;  it  contains  no  oxygen,  and  is  hence  employed 


VEGETABLE  SUBSTANCES.          399 

for  protecting  the  more  oxidable  metals,  as  potassium  and  sodium,  from 
oxidation. 

Petroleum,  found  in  several  parts  of  the  world,  especially  in  coal 
districts,  is  of  a  reddish-brown  colour,  unctuous  to  the  touch,  and  less 
limpid  than  naptha.  Mineral  tar  is  very  similar  to  petroleum,  but  is 
more  viscid  and  of  a  deeper  colour.  From  the  petroleum  of  Rangoon 
Dr.  Christison  has  obtained  a  white,  pearly,  crystalline,  inflammable 
substance,  to  which  he  has  given  the  name  of  petroline. 

Asphaltum  is  found  on  the  banks  of  the  Dead  sea,  and  occurs  in  large 
quantity  in  Barbadoes  and  Trinidad.  It  is  solid,  brittle,  of  a  black 
colour,  vitreous  lustre  and  conchoidal  fracture  ;  it  melts  easily,  and  is 
very  inflammable. 

Mineral  Pitch  or  Maltha  is  likewise  a  solid  bitumen,  but  is  much  soft- 
er than  asphaltum.  The  elastic  bitumen,  or  Mineral  caoutchouc,  is  a 
rare  variety  of  mineral  pitch,  found  only  in  the  Odin  mine,  near  Cas- 
tleton,  in  Derbyshire,  England. 

Retinasphaltum  is  a  peculiar  bituminous  substance,  found  associated 
with  the  brown  coal  of  Bovey  in  Devonshire,  and  described  by  Mr. 
Hatchett.  It  consists  partly  of  bitumen,  and  partly  of  resin,  a  com- 
position which  led  Mr.  Hatchett  to  the  opinion  that  bitumens  are 
chiefly  formed  from  the  resinous  principle  of  plants. — Phil.  Trans. 
1804. 

Pit  Coal. — This  is  a  general  term  often  applied  to  several  varieties, 
and  even  distinct  species.  Brown  coal  is  characterized  by  burning  with 
a  bituminous  odour.  It  sometimes  has  a  fibrous  structure,  and  hence 
this  variety  is  called  bituminous-wood.  Pitch  coal  or  jet,  which  is  em- 
ployed for  forming  ear-rings  and  other  trinkets,  is  intermediate  between 
the  brown  and  black  coal.  Black  or  common  coal,  of  which  there  are 
several  varieties,  is  extensively  employed  for  fuel. 

Glance  Coal  or  Anthracite,  abundant  in  Pennsylvania,  differs  from 
common  coal  in  containing  no  bituminous  substances,  and  in  not  yield- 
ing inflammable  gases  by  distillation.  It  is  nearly  pure  carbon,  and 
consequently  it  burns  without  flame. 

REFERENCES  For  localities  of  the  Bitumens  above  noticed,  and  further 
information  concerning  them,  see  Cleaveland's  Mineralogy.  Thomson  on  the 
composition  of  different  species  of  Pit  Coal,  Ann.  of  Phil,  xiv,  81.  Ure's 
analysis  of  Splint  and  Cannel  Coal,  Phil.  Trans.  1822,  471.  Karsteiis  ob- 
servations and  experiments  on  different  kinds  of  Coal ;  a  very  valuable  trea- 
tise, of  which  an  abstract  trill  be  found  in  Jameson's  Edin.  New  Phil.  Jour. 
ji.  280,  and  iii.  60,  322. 

SECTION  IV. 

SUBSTANCES,  THE    OXYGEN  AND  HYDROGEN    OF    WHICH    ARE    IN 
EXACT  PROPORTION   FOR  FORMING  WATER. 

Sugar. 

Sugar  is  an  abundant  vegetable  product,  existing  in  a  great  many 
ripe  fruits,  in  the  juice  of  the  maple,  Acer  Sacc/iarinum,  L.  in  the 
beet  root,  &c.  But  the  plant  which  contains  it  in  the  greatest  quan- 


400         VEGETABLE  SUBSTANCES. 

tity  is  the  sugar  cane,  from  which  nearly  all  the  sugar  used  in  this 
country  is  obtained.  When  pure,  sugar  is  a  white  crystalline  sub- 
stance, of  a  purely  sweet  taste,  and  without  odour  ;  it  is  easily  soluble 
in  cold  water,  and  in  almost  any  proportion  in  hot,  the  solution  con- 
stituting syrup,  which,  by  long  repose  deposits  crystals  of  sugar  ;  it  is 
loluble  in  alcohol,  and  large  crystals  may  be  obtained  from  the  alco- 
holic solution  ;  it  combines  with  alkalies  and  alkaline  earths,  forming 
compounds,  in  which  the  taste  of  the  sugar  is  greatly  injured,  but 
which  may  be  restored  by  the  addition  of  an  acid  ;  when  triturated 
with  oil  it  forms  a  mixture  which  is  diffusible  through  water,  producing 
a  milky  fluid,  called  an  emulsion ;  when  exposed  to  the  action  of  nitric 
acid  it  is  converted  into  oxalic  acid. 

Manna,  Sugar  of  Grapes,  of  the,  Maple,  of  Beets,  ffC.  are  varieties  of 
sugar,  and  possess  the  same  general  properties.  Honey  consists  prin- 
cipally of  a  crystallizable  and  an  uncrystallizable  sugar.  Molasses  is 
an  uncrystallizable  sugar. 

REFERENCES.  For  detailed  accounts  of  the  manufacture  of  Sugar,  see 
Edwards1  History  of  the  West  Indies  ;  and  Aikiri's  and  Ures  Chem.  Did. 
For  papers  on  the  making  of  Sugar  from  Beets,  see  Repert.  of  Arts,  2d  ser. 
i.  vii.  xxii.  xxviii.  xxix.  xl.  Ohaptal  on  the  same  subject,  Ann.  de  Cliim. 
xcv.  2o3.  or  Ann.  of  Phil.  ix.  50.  On  the  same  subject,  see  also  Franklin 
Jour*  ii.  183.  Howard's  celebrated  process  for  preparing  and  refining  Su- 
gar, are  fully  described  in  the  Repert.  of  Arts,  xxiii.  129,  xxv.  257.  On  the 
composition  of  Sugar  >  see  Prout's  Essay  on  Alimentary  Substances,  PhiL 
Mag.  and  Ami.  iii.  98. 

Starch  or  Fecula. 

Starch  exists  in  a  great  variety  of  vegetables,  being  one  of  the  ehief 
ingredients  of  most  kinds  of  grain,  and  of  some  roots,  as  the  potatoe, 
from  which  it  may  be  extracted  by  diffusing  the  powdered  grain  or 
rasped  root  in  cold  water,  and  separating  the  grosser  parts  by  a  strain- 
er. It  is  a  white  pulverulent  substance,  without  taste  or  smell ;  it  i» 
insoluble  in  alcohol,  ether  or  cold  water,  but  is  easily  dissolved  in  boil- 
ing water  ;  it  forms  a  blue  colour  with  iodine,  by  which  it  may  be  dis- 
tinguished from  all  other  substances  ;  it  unites  with  alkalies,  forming 
a  compound,  soluble  in  water,  from  which  the  starch  is  thrown  down, 
by  acids  ;  is  decomposed  by  strong  sulphuric  acid,  and  by  nitric  acid, 
assisted  by  heat,  is  converted  into  oxalic  and  malic  acids. 

Amidine,  a  term  applied  to  torefied  starch— that  is,  starch  modified 
by  heat,  whether  in  the  dry  way  or  by  boiling  water.  It  yields  a  blue 
colour  with  iodine,  and  is  soluble  in  cold  water. 

Hordein. — A  name  given  by  Proust  to  a  peculiar  principle  contained 
in  barley,  which  he  supposed  to  be  converted,  in  malting,  partly  into 
starch,  and  partly  into  sugar.  Dr.  Thomson,  however,  considers  it 
merely  a  modification  of  starch. 

According  to  Caventou,  Indian  arrow  root,  prepared  from  the  root 
of  the  Maranta  arundinacea,  L.,  has  all  the  characters  of  pure  starch. 
Sago,  obtained  from  the.  pith  of  an  East  Indian  palm  tree,  Cycas  cir- 
dnalis,  L.  and  Tapioca,  from  the  root  of  the  Jatropa  manihot,  L.  (Jan- 
nipha  manihot,  Kunth,)  are  chemically  the  same  substance.  They  both 
exist  in  the  plants  from  which  they  are  extracted,  in  the  form  of  starch  ; 


VEGETABLE  SUBSTANCES.          401 

feut  as  heat  is  employed  in  their  preparation,  the  starch  is  more  or  less 
converted  into  amidne.  From  this  it  follows  that  pure  potatoe  starch 
may  be  used  instead  of  arrow  root,  and  that  the  same  material,  modi- 
fied by  heat,  woud  afford  a  good  substitute  for  sago  and  tapioca. — Tur- 
ner. 

REFERENCES.  Skrimshire  on  the  quantity  of  Starch  in  the  different  varie 
ties  of  Potato?,  and  the  methods  of  separating  it,  Nicholson's  Jour.  xxi. 
Pearson's  experiments  and  observations  on  Potatoe  Starch,  Repert.  of  Arts, 
list  Ser.  iii.  383.  Lampadius'  analysis  of  four  different  varieties  of  Potatoet 
Ann  of  Phil.  v.  39.  For  a  notice  of  the  papers  of  Saussure,  Guibourt,  Cat> 
entou,  and  others,  see  Henry's  Client,  ii.  272.  Proufs  essay  on  alimentary 
substances,  Phil.  Mag.  and  Ann.  iii.  98. 

Gum. 

Of  this  proximate  principle  Gum  Arabic  may  be  taken  as  an  exam- 
ple. It  is  the  concrete  juice  of  several  species  of  Mimosa  or  Acacia, 
natives  of  Africa  and  Arabia.  It  occurs  in  small  rounded,  transparent, 
friable  grains,  commonly  of  a  pale-yellow  colour,  inodorous  and 
nearly  tasteless  ;  it  is  soluble  in  water,  and  forms  a  solution  called 
mucilage ;  is  insoluble  in  alcohol  and  ether,  and  the  former  precipi- 
tates it  from  its  solution  in  water ;  is  soluble  in  alkaline  solutions  and 
in  lime  water,  and  is  precipitated  unchanged  by  acids  ;  is  decomposed 
by  dilute  acids,  and  by  the  action  of  strong  nitric  acid  is  converted 
into  Mucic  or  Saccholactic  Acid ;  it  is  not  altered  by  exposure  to  the 
air,  but  its  solution  at  length  becomes  sour  and  gives  out  an  odour  of 
acetic  acid  ;  it  is  precipitated  from  its  solution  by  several  metallic  salts, 
especially  sub  acetate  of  lead. 

Besides  gum  arabic,  there  are  several  well  marked  kinds  of  this 
principle,  especially  the  gum  tragacanth,  cherry-tree  gum,  and  the  mu- 
cilage from  linseed,  each  of  which  presents  some  peculiarities. 

REFERENCES.  For  a  good  Account  of  the  production  and  gathering  of 
Gum  Arabic,  see  Aikirfs  Chem~  Diet.  art.  Mucilage.  For  various  analyses 
af  Gum,  by  Ure  and  others,  see  Henry,  ii.209.  Bostock  on  Vegetable  Jelly, 
Nicholsons  Jour,  xviii.  28.  For  a  notice  of  several  varieties  of  gum  and 
vegetable  mucilage.  See  Berzclius,  Traite  de  Chim.  v.  214. 

Lignin. 

The  woody  fibrs  which  remains  after  the  action  of  water  and  alco- 
hol on  wood,  has  been  called  lignin.  [t  is  insipid  and  inodorous,  un- 
dergoes no  change  by  keeping  ;  by  the  action  of  sulphuric  acid  it  is 
converted  into  a  substance  like  gum,  and  by  diluted  sulphuric  acid 
this  is  converted  into  sugar ;  by  destructive  distillation  it  yields  Pyro- 
ligneous  acid,  and  a  bright  shining  charcoal  remains.  —  See  the  references 
under  Acetic  Acid. 


402  VEGETABLE    SUBSTANCES- 


SUBSTANCES    WHICH,  SO  FAR  AS  IS  KNOWN,  DO  NOT    BELONG  TO 
ANY  OF  THE  PRECEDING  SECTIONS. 

Colouring   Matter. 

The  Colouring  Matter  of  Vegetables  does  not  appear  to  reside  in  any 
peculiar  principle,  and  is  therefore  differently  affected  by  solvents, 
By  the  affinity  of  certain  solvents,  colouring  matter  is  separated  from 
vegetables,  and  by  the  superior  attraction  of  silk,  wool,  cotton,  &c. 
it  is  separated  from  the  solvents  and  attracted  to  the  fibres  of  the 
fabric. 

Colours  which  are  fixed  and  durable,  by  the  simple  attraction  of  the 
fibres  of  ctoth,  without  the  intervention  of  any  other  substance,  are 
called  Substantive  Colours.  Those  which  require  the  intervention  of  a 
third  body,  which  possesses  an  attraction  both  for  the  cloth  and  the 
colouring  matter,  and  thus  links  them  together,  are  called  Adjective 
Colours.  The  substance  which  possesses  the  property  of  fixing  co- 
lours, is  called  a  mordant  or  basis.  The  mordants  in  most  common 
use  are  alumina,  oxide  of  iron  and  oxide  of  tin.  Alumina  has  a  very 
strong  attraction  for  colouring  nmtter,  and  forms  insoluble  compounds, 
called  lakes. 

Though  there  is  a  great  variety  in  the  tints  observable  in  dyed  stuffs, 
they  may  all  be  produced  by  four  simple  ones,  viz.  blue,  red,  yellow 
and  black. 

Blue  Dyes.  — The  most  important  of  these  is  Indigo,  -the  produce  of 
several  species  of  Indigofera.  It  is  a  brittle  substance,  of  a  deep  blue 
colour,  and  without  either  taste  or  odour  ;  when  heated  to  550°  F.  a 
fine  violet  vapour  arises,  which  condenses  into  acicular  crystals,  call- 
ed Indigogene.  [Gorham,  in  JY*.  Eng.  Jour.']  It  is  soluble  in  concen- 
trated sulphuric  acid,  and  the  solution  forms  the  Saxon  Blue;  it  con- 
tains oxygen  in  its  natural  state,  and  when  deoxidized  has  a  green 
tint,  and  is  then  soluble  in  alkalies,  and  may  be  fixed  on  cloth,  which 
acquires  the  blue  colour  by  exposure  to  the  air. 

The  indigo  of  commerce  is  of  a  very  complex  nature,  containing,  ac- 
cording to  Berzelius,  in  addition  to  the  salts  of  magnesia  and  lime,  the 
following  ingredients: — 1.  A  glutinous  matter;  2.  Indigo-brown ;  3. 
Indigo-red ;  4.  Indigo-blue. 

Cerulin  and  Phcnicin,  are  two  compounds  of  indigo  and  water,  de- 
scribed by  Mr.  Crum  ;  but  Berzelius  supposes  them  to  be  of  a  more 
complicated  nature. — See  Crum  on  Indigo  and  on  certain  substances  pro- 
duced from  it  by  means  of  Sulphuric  Acid,  Ann,  of  Phil.  xxi.  81. 

Red  Dyes. — The  chief  substances  which  are  employed  for  giving  thfl 
red  dyer  are  Cochineal,  an  insect  feeding  upon  several  varieties  of  Cac 
lus  ;  archil,  the  produce  of  the  l}armelia  roccella,  Ach.,  a  lichen  grow« 
ing  in  the  Canary  Islands  ;  madder,  the  root  of  the  Rubia  tinctorum, 
L.;  Brazil-wood,  or  the  wood  of  the  Ccesalpinia  echinata,  Lam.;  log- 
wood, or  that  from  the  Hccmatoxylon  campechianum,  L.  of  tropical 
America  :  and  safflower,  or  the  dried  flowers  of  the  Carthamus  tinctori- 
us,  L.  These  are  all  adjective  colours. 


VEGETABLE  SUBSTANCES.         403 

The  blue  pigment  called  Litmus  or  Turnsol,  used  as  a  test,  is  a  com- 
pound of  the  red  matter  of  the  archil  and  an  alkali.  Cudbear  is  an  ar- 
ticle of  a  similar  kind  manufactured  at  Glasgow.  It  is  used  in  dying, 
and  as  a  chemical  test. 

Yellow  Dyes. — The  chief  of  these  are  the  quercitron,  or  Quercus 
tinctoria,  IV.;  several  species  of  American  hickory  ;  turmeric,  or  the 
root  of  the  Curcuma  longa,  L.;  fustic,  or  the  wood  of  the  Morus  tinc~ 
toria,  L.,  of  the  West  Indies  ;  all  adjective  colours. 

Black  Dyes. — The  black  dye  is  made  of  the  same  ingredients  as 
writing  ink  ;  and  therefore  consists  essentially  of  a  compound  of  ox- 
ide of  iron,  with  gallic  acid  and  tannin.  By  the  addition  of  logwood 
and  acetate  of  copper,  the  black  receives  a  shade  of  blue. 

REFERENCES.  For  full  details  on  the  subject  of  Dying,  4"c<j  see  Berthol- 
Let  on  Dying;  Bancroft's  Researches  on  Permanent  Colours,  Calico- Print* 
in.g,  <SfC.;  Dr.  T.  Cooper  on  the  same  ;  Parties'  Chem.  Essays,  ii.  63;  apaper 
by  Mr.  Henry,  in  the  third  volume  of  the  Manchester  Memoirs  ;  and  the  Es- 
say of  Thenard  and  Roard,  in  Ann.  de  Chun.  Ixxiv.  For  account  of  thy 
recent  researches  of  Berzelius,  Liebig,  fyc.  on  Indigo^  see  Henry's  Chem.  ii. 
or  Berzelias,  Traiiede  Chim. 

Tannin. 

This  substance  exists  in  large  quantity  in  the  excrescences  of  seve- 
ral species  of  the  oak,  called  gall-nuts,  and  also  in  the  bark  of  several 
trees,  and  in  many  other  vegetables.  It  is  difficult  to  obtain  it  in  a 
pure  state,  and  hence  its  nature  and  composition  are  still  obscure.  In 
its  dry  state  it  is  a  brown  friable  substance,  of  a  resinous  fracture,  in- 
soluble in  pure  alcohol,  but  soluble  in  water  ;  its  aqueous  solution  has 
a  brown  colour,  and  is  said  not  to  become  mouldy  by  keeping  ;  it  has 
a  strong  attraction  for  alkalies,  forming  compounds  which  are,  for  the 
most  part,  sparingly  soluble  in  water ;  it  is  precipitated  from  its  solu- 
tion by  most  of  the  acids,  and  by  alkaline  bases. 

The  most  characteristic  property  of  tannin  is  its  action  upon  the 
salts  of  the  peroxide  of  iron  and  solution  of  gelatin.  With  the  former 
it  causes  a  black  precipitate  ;  with  the  latter  an  insoluble  yellowish  pre- 
cipitate, called  tanno-gelatin,  which  is  the  essential  basis  of  leather, 
being  always  formed  when  skins  are  macerated  in  an  inlusion  of 
bark.  » 

Artificial  Tannin. — A  very  interesting  substance,  discovered  by  Mr. 
Hatchett,  and  obtained  by  the  action  of  nitric  acid  on  animal  or  vege- 
table charcoal,  and  several  other  substances.  It  is  a  brown  fusible 
substance,  of  a  resinous  fracture  and  astringent  taste  ;  is  soluble  in 
cold  water,  reddens  litmus,  and  acts  like  natural  tannin  upon  salts 
ef  iron  and  solution  of  gelatin. 

REFERENCES.  Fir  H.  Davy  on  the  process  of  Tanning,  Repert.  of  Arts, 
*S.d.  ser.  iii.  435.  The  article  Tannin  in  Ure's  Chem.  Diet.  4M.  ed.  contains  a 
Table  of  the  proportion  of  Tawiin  indifferent  Vegetable  Products,  coin  filed 
from  the  experiments  of  Sir  H.  Davy,  Biggins  and  Cadet  de  Gasstncourt. 
Aikin's  Chem.  Diet.  Art.  Leather  and  Gelatin,  contains  an  account  of  the  pro- 
cess  of  T,undn<f.  Hatchdl,  on  Artificial  Tanning,  Phil.  Trans.  1805  a/id 
1806,  or  Repert.  of  Arts,  2d.  ser.  viii. 


404          VEGETABLE  SUBSTANCES. 

Gluten— Yeast —  Vegetable  Albumen. 

Gluten. — This  is  obtained  from  wheat  flour,  by  making  it  into  a  paste 
and  kneading  it  under  a  small  stream  of  water.  The  fluid  becomes 
milky,  carries  off  the  starch,  and  gluten  remains.  It  is  of  a  grayish 
colour,  fibrous  structure,  tough  and  elastic,  and  when  stretched  into 
thin  pieces,  appears  like  animal  membrane  ;  it  has  scarcely  any  taste  ; 
is  insoluble  in  water,  alcohol  and  ether  ;  it  is  soluble  both  in  acids  and 
alkalies ;  when  kept  in  a  warm  and  moist  situation  it  ferments,  and 
becomes  acid,  but  in  a  few  days  putrefies,  and  gives  out  an  offensive 
odour,  like  that  of  putrifying  animal  matter ;  during  its  putrefaction 
two  new  substances  are  formed,  called  by  Proust  Caseous  Oxide 
and  Caseic  Acid,  identical  with  the  principles  which  are  generated  dur- 
ing the  fermentation  of  the  curd  of  milk. 

Gluten  is  contained  in  most  grains,  and  it  is  the  most  nutritive  of 
all  vegetable  substances.  To  this,  wheat  flour  owes  its  property  of 
forming  a  tenaceous  paste  with  water,  and  the  carbonic  acid  evolved 
during  the  fermentation  of  dough,  producing  what  is  called  the  rising 
of  the  dough,  is  detained  by  the  viscid  gluten,  and  thus  forms  light, 
spongy  bread. 

There  appear  to  be  two  distinct  principles  in  gluten,  called  by  M. 
Taddei,  the  discoverer,  Gliadine  and  Zimome.  The  former  is  a  brit- 
tle, slightly  transparent  substance,  of  a  yellow  colour,  and  soluble  in 
alcohol  ;  the  latter,  a  hard  and  tough  substance,  insoluble  in  that 
menstruum.  But  the  existence  of  these  principles  is  denied  by  Ber- 
zelius. 

Yeast. — This  substance  is  always  generated  during  the  vinous  fer- 
mentation of  vegetable  juices  and  decoctions,  rising  to  the  surface  in 
the  form  of  a  frothy,  flocculent,  somewhat  viscid  matter,  the  nature 
and  composition  of  which  are  unknown.  It  is  insoluble  in  water  and 
alcohol,  and  in  a  warm  atmosphere  gradually  putiifies  ;  when  heated 
moderately  it  becomes  dry  and  hard,  and  may  then  be  preserved  with- 
out change.  Its  most  remarkable  property  is  that  of  exciting  ferment- 
ation. 

Vegetable  Albumen. — A  substance  coagulable  by  heat,  and  which 
is  very  analogous  to  animal  albumen  or  curd.  It  was  found  in  the 
bitter  almond  by  Vogel,  in  the  sweet  almond  by  M.  Boullay,  and  pro- 
bably exists  in  most  of  the  emulsive  seeds. — Ann.  of  Phil.  xii.  39. — 
Tamer. 

REFERENCES.  Proust  on  Caseous  Oxide  and  Caseic  Acid  in  Gluten, 
Brands' s  Jour.  vii.  389.  Taddti  on  the  Gluten  of  Wheat,  and  on  Gliadine 
and  Zimome,  Ann.  of  Phil.  xv.  390.  Vogel' 's  analysis  of /he  Ceretdia,  Ann. 
of  Phil.  xi.  344.  Bostock  on  the  partial  solubility  of  Gluten  in  wafer  by 
long  digestion,  Nicholson's  Jour,  xviii.  34.  On  the  proportion  of  G'uten  in 
different  kinds  of  Wheat,  see  Davys  Agricultural  Chemistry.  M.  Henry,  of 
Paris,  on  the  same  subject,  Ami.  de  Chim.  et  de  Phys.  x!.  22-'*. 


VEGETABLE  SUBSTANCES.          405 


SECTION  VI. 


FERMENTATION. 

Under  this  head  may  be  classed  the  spontaneous  changes  to  which 
some  vegetable  substances  are  liable,  and  they  may  be  divided  into  five 
distinct  kinds,  viz.,  the  panary,  the  saccharine,  the  vinous,  the  acetous, 
and  the  putrefactive  fermentation. 

Panary  fermentation. — This  name  has  been  applied  to  the  changes 
which  take  place  in  dough  during  the  formation  of  bread.  It  has  been 
observed  that  carbonic  acid  is  the  agent  in  raising  the  dough  ;  this  is 
evolved  by  the  reaction  on  the  materials,  aided  by  the  ferment  which 
is  added.  It  is  maintained  by  Dr.  Colquhoun,  that  all  flour  contains 
about  five  per  cent,  of  sugar, — that  the  starch  and  gluten  do  not  ne- 
cessarily undergo  any  change  in  the  fermentation  of  dough, — and  that 
the  conversion  of  sugar  into  alcohol  and  carbonic  acid,  is  the  essential 
part  of  the  panary  process  ;  and  the  escape  of  those  volatile  products 
in  the  oven,  leaves  the  bread  full  of  little  cells  or  vesicles.  This  view 
has  been  confirmed  by  Mr.  Graham,  who  obtained  from  bread  alcohol 
of  sufficient  strength  to  fire  gun-powder. — Colquhoun' s  Chemical  Essay 
on  the  art  of  Baking  Bread,  Ann.  of  Phil,  xxviii.  161,  263.  Graham, 
same  work  and  volume,  263. 

Saccharine  fermentation. — The  only  substance  known  to  be  subject  to 
this  kind  of  fermentation  is  starch. 

When  gelatinous  starch  or  amidine  is  kept  in  a  moist  state  for  a 
considerable  length  of  time,  a  portion  of  sugar,  about  equal  to  half  its 
weight,  is  generated.  By  the  access  of  air  the  quantity  of  sugar  is  in- 
creased. 

The  germination  of  seeds  and  the  ripening  of  fruits  have  also  been 
regarded  by  some  chemists  as  examples  of  that  kind  of  fermentation. 

Vinous  fermentation. — The  conditions  necessary  to  this  process  are, 
the  presence  of  sugar,  water,  yeast  or  some  ferment,  and  a  certain 
temperature.  When  one  part  of  sugar  is  dissolved  in  five  parts  of  wa 
ter,  and  a  little  yeast  added,  fermentation  quickly  takes  place  if  the 
mixture  be  exposed  to  the  temperature  of  about  6(P  or  70°  F.  A 
brisk  intestine  motion  ensues,  and  the  liquor  becomes  turbid.  Some 
impurities  are  separated  and  a  frothy  scum  rises  to  the  surface.  A  his- 
sing noise  is  heard,  carbonic  acid  gas  is  evolved,  and  the  bulk  of  the 
liquid  is  augmented  and  its  temperature  is  increased.  After  some  time 
these  phenomena  cease,  the  liquor  becomes  clear,  and  having  lost  its 
sweetness,  has  acquired  a  spiritous  taste  and  smell,  and  is  intoxica- 
ting. This  is  spirit  of  wine,  and  when  properly  purified,  constitutes 
alcohol. 

The  presence  of  yeast  is  not  essential  to  vinous  fermentation.  The 
juices  of  many  vegetables  contain  the  saccharine  principle  essential  to 
this  process,  together  with  several  other  substances  which  promote  it. 
Thus  from  the  fermented  juice  of  the  grape  or  wine,  brandy  is  procur- 
ed by  distillation  ;  rum  is  procured  from  the  fermented  juice  of  the  su- 
gar-cane ;  whiskey  from  the  fermented  decoction  of  grain  ;  and  arrack 
from  fermented  rice.  The  various  kinds  of  ale  and  beer  are  produced 
from  a  decoction  of  nutritive  grains  previously  malted  ;  and  they  dif- 
fer from  wines,  in  containing  a  large  quantity  of  mucilaginous  and  ex- 
tractive matter  derived  from  the  malt. 


406          VEGETABLE  SUBSTANCES. 

Acetous  fermentation. — When  any  of  the  vinous  liquors  aie  exposed 
to  the  free  access  of  atmospheric  air  at  a  temperature  of  80J  or  85°, 
they  undergo  a  second  fermentation,  terminating  in  the  production  of 
a  sour  liquid,  called  vinegar.  During  this  process  a  portion  of  the 
oxygen  of  the  air  is  converted  into  carbonic  acid  ;  hence,  unlike  vin- 
ous  fermentation,  the  contact  of  the  atmosphere  is  necessary  ;  and  the 
most  obvious  phenomenon  is,  the  removal  of  carbon  from  the  beer  or 
wine  [Branrfe.]  Vinegar  is  usually  obtained  from  malt  liquor  or  cider  ; 
but  wine  is  employed  in  those  countries  where  the  grape  is  abundantly 
cultivated. 

A  most  important  improvement  has  recently  been  introduced  into  the 
manufactory  of  vinegar,  which  it  is  said  is  already  extensively  prac- 
ticed on  the  continent  of  Europe.  The  introduction  of  this  improve* 
ment  is  chiefly  due  to  Mitscherlich.  It  is  founded  on  the  principle 
that  alcohol,  by  absorbing  oxygen,  is  changed  into  acetic  acid  and  wa- 
ter. 

This  oxidation  is  promoted  by  the  process  of  fermentation  ;  and 
when  the  fermentation  has  begun,  is  much  accelerated  by  the  presence 
of  acetic  acid.  The  oxidation  is  effected  entirely  at  the  expense  of 
the  oxygen  of  the  air  ;  to  accelerate  the  process,  therefore,  by  produc- 
ing as  many  points  of  contact  as  possible  between  the  liquid  and  the 
air,  the  following  arrangement  is  adopted.  A  large  cask  is  taken, 
placed  upright  with  a  stop-cock  at  the  bottom,  and  a  series  of  holes, 
half  an  inch  in  diameter,  bored  in  each  stave,  a  few  inches  above  it. — 
It  is  then  nearly  filled  with  chips  or  shavings  of  wood,  previously  steep* 
ed  in  strong  vinegar  till  they  are  perfectly  saturated.  Within  the  upper 
part  of  the  cask  a  shallow  cylindrical  vessel  is  placed,  nearly  in  con- 
tact with  the  shavings,  the  bottom  of  which  is  perforated  with  many 
small  holes,  each  partially  stopped  with  a  slender  twig  which  passes  an 
inch  or  two  beneath  the  perforated  bottom  of  the  cylinder.  The  alco- 
hol diluted  with  eight  or  nine  parts  of  water,  and  mixed  with  the  fer- 
menting substance,  is  now  poured  into  the  cylinder,  through  the  bot- 
tom of  which  it  trickles,  drop  by  drop,  upon  the  shavings  below,  be- 
comes oxidized  in  its  passage,  and  runs  out  at  the  stop  cock  beneath, 
already  converted  almost  entirely  into  vinegar.  The  air  rushes  in  by 
the  holes  beneath,  and  passes  out  above  by  eight  glass  tubes,  cemented 
for  that  purpose  into  the  bottom  of  the  cylinder  ;  and  so  rapidly  is  it 
deprived  of  its  oxygen,  that  when  it  escapes  above,  it  extinguishes  a 
candle.  During  the  process  much  heat  also  is  developed  ;  so  that  from 
the  temperature  of  60°  F.  (that  of  the  room),  the  interior  of  the  cask 
rises  as  high  as  86 J  F.  In  the  proper  regulation  of  this  temperature, 
much  of  the  difficulty  consists. 

A  second  transmission  of  the  acid  thus  obtained,  through  another 
similar  cask,  finishes  the  process.  The  whole  is  concluded  in  a  few 
hours;  four  and  twenty  are  considered  amply  sufficient  to  convert  a 
given  quantity  of  alcohol  into  vinegar. — Johnston's  Report. 

Putrefactive  fermentation. — Certain  vegetable  bodies  when  exposed 
to  air,  moisture  and  to  a  temperature  of  from  6(P  to  100-  F.,  are  com- 
pletely decomposed,  or  in  other  words,  undergo  the  process  of  pvtre- 
faction.  Those  proximate  principles  in  which  carbon  and  hydrogen 
prevail,  such  as  the  oils,  resins  and  alcohol,  do  not  putrefy;  nor  do 
the  acids  which  contain  a  considerable  excess  of  oxygen,  suffer  this 
change.  Those  substances  only  are  disposed  to  putrefy,  in  which 
the  oxygen  and  hydrogen  are  in  proportion  to  form  water  ;  and  even 
among  these  a  great  difference  is  observable.  During  this  process 


VEGETABLE  SUBSTANCES.          407 

various  gases  are  evolved ;  but  its  theory  is  not  understood.  The 
chemical  action  is  probably,  in  some  instances,  energetic,  since  light 
is  evolved  by  putrescent  wood,  and  it  becomes  phosphorescent. 

REFERENCES.  For  examing  the  results  of  Vinous  Ferment  a  ion,  see  an 
apparatus  in  Lavoisier1  s  Chemistry,  and  Henry,  ii.  365.  Chaplafs  Treatise 
on  the  Vine  and  on  Making  Wines.  Henderson  on  Wines ;  and  an  article 
on  it  in  Quarterly  Review,  xxxii.  232.  Ohaptal  on  the  fermentation  of  Winef 
llepert.  of  Arts,  \stser.  xiii  353,  407,  Dupontal's  observations  on  fermenta- 
tion, from  the  Ann.  de  Chim.  Repert.  of  Arts,  2d  ser.  \\\  239.  Thenard 
on  the  same  subject,  same  work,  2d  ser.  iv.  67.  13'K  Dr.  Cooper's  Letters  on 
Foreign  and  Domestic  Wines,  Emporium  of  Arts,  iii.  and  iv.  The  arti- 
cle Brewing,  in  the  Edinburgh  Encyclopedia,  and  in  the  Supplement  to  the 
Encyclopedia  Britaniiica,  the  latter  byJ.Farey.  Muvh  interesting  and  va* 
htable  inform  ition  on  Brewing,  Distilling,  Wine-Making,  Baking,  fyc.,  icUl 
be  found  in  a  volume  by  Mr.  Donovan,  in  Dr.  Lard  net's  Cabinet 
Saussure,  Recherches  Chimiques  sur  la  Vegetation* 


408  ANIMAL   SUBSTANCES. 


CHAPTER  X. 


ANIMAL  SUBSTANCES. 

All  distinct  compounds  which  are  derived  from  the  bodies  of  ani- 
mals, are  denominated  Proximate  Animal  Principles.  They  are  dis- 
tinguished from  vegetable  matter  by  the  presence  of  nitrogen,  by 
their  strong  tendency  to  putrefy,  and  the  highly  offensive  products  to 
which  their  spontaneons  decomposition  gives  rise.  But  it  has  already 
been  observed  that  some  vegetable  substances  likewise  contain  nitro* 
gen,  and  again  a  few  of  them  undergo  the  putrefactive  fermentation. 
It  should  also  be  stated  that  some  compounds  of  animal  origin  con- 
tain no  nitrogen,  and  are  not  disposed  to  putrefy. 

The  main  ingredients  of  animal  matter  are  carbon,  oxygen,  hydro- 
gen and  nitrogen  ;  in  addition  to  which,  other  substances  are  occa- 
sionally found  in  small  quantity,  as  sulphur,  phosphorus,  iron,  and 
earthy  and  saline  matters. 

When  heated  in  close  vessels,  animal  substances  yield  water,  car- 
bonic oxide,  carburetted  hydrogen,  probably  free  nitrogen  and  hydro- 
gen, the  carbonate  and  hydrocyanate  of  ammonia,  and  a  peculiarly 
retid  thick  oil.  They  may  be  analyzed  or  reduced  to  their  ultimate 
elements  in  the  same  manner  as  vegetable  substances. 

I  shall  briefly  notice  these  substances  in  the  following  order. 

1.  Animal  acids. 

2.  Oleaginous  substances. 

3.  Substances  which  are  neither  acid  nor  oleaginous. 

4.  The  more  complex  animal  substances. 

SECTION  I. 

ANIMAL    ACIDS. 

Several  acids  are  found  in  animal  bodies,  which  belong  equally  to 
the  mineral  and  vegetable  kingdoms,  and  which  have  been  previously 
described,  as  as  the  sulphuric,  phosphoric,  muriatic,  carbonic,  benzoic, 
acetic,  <fec.  In  this  section  are  included  those  acids  only,  which  are 
•upposed  to  be  peculiar  to  animal  bodies. 

Uric  Mid.— Atom.  Num.  72—  Symb.  O+2N+6C. 

Discovered  by  Scheele  in  1776.  It  is  a  common  constituent  of 
urinary  and  gouty  concretions,  and  is  always  present  in  healthy  urine, 
combined  with  ammonia,  or  some  other  base,  and  in  the  urine  of  the 
Boa  Constrictor,  and  other  serpents. 


ANIMAL   SUBSTANCES.  409 

PROPERTIES.  Pure  uric  acid  is  a  white  powder,  which  is  tasteless 
and  inodorous  ;  it  is  insoluble  in  alcohol ;  very  sparingly  soluble  in 
cold  or  hot  water,  requiring,  according  to  Prout,  10,000  times  its 
weight  of  that  fluid  at  60J  F.  for  solution  ;  it  reddens  litmus,  and 
unites  with  bases,  forming  salts,  which  are  called  urates  or  lithates ; 
it  undergoes  no  change  by  exposure  to  air ;  is  decomposed  by  chlo- 
rine, but  is  not  acted  upon  by  any  acid  except  the  nitric,  with  which 
it  produces  a  beautiful  purple  colour. 

PREPARATION.  This  acid  may  be  obtained  from  urinary  calculus,  of 
which  it  is  one  of  the  most  common  ingredients,  by  reducing  it  to 
powder  in  solution  of  potassa,  decomposing  the  clear  solution  by  ex- 
cess of  muriatic  acid,  washing  the  precipitate  with  a  large  quantity  of 
distilled  water,  and  drying  it  at  212°  F. 

REFERENCES.  Proufs  essays  on  Calculous  diseases.  Thomson  on  Uric 
Acid,  First  Princ.  ii.  155.  Dr.  Henry  on  the  Urates,  Manchester  Memoirs, 
N.  S.  ii. 

Pifi'O-Uric  Add. — Tbis  acid  is  obtained  by  subjecting  uric  acid  to 
heat.  It  occurs  in  the  form  of  white  acicular  crystals  ;  is  soluble  in 
boiling  alcohol,  and  in  forty  times  its  weight  of  water  ;  it  is  not  de- 
composed by  digestion  in  nitric  acid,  [l.hevallier  and  Lassaignc,  .-/Tin. 
of  Phil.  xvi.  25.]  This  acid  is  now  supposed  to  be  identical  with  the 
cyanuric  acid  of  Leibigand  Wbhler. 

Purpuric  Add.  —This  was  first  recognized  as  a  distinct  acid  by 
Prout.  It  occurs  in  the  form  of  a  powder,  which  is  very  sparingly 
soluble  in  water  ;  does  not  redden  litmus,  though  it  has  the  power  of 
saturating  alkalies ;  it  is  insoluble  in  ether,  alcohol  and  dilute  mine- 
ral acids,  but  is  readily  dissolved  by  the  concentrated  ones ;  its  most 
distinguishing  character  is  its  tendency  to  form  red  or  purple  salts, 
called  Purpurates,  though  this  is  denied  by  Vauquelin. 

REFERENCES.  Prout,  in  Phil.  Trans.  1818.  Lassaign^  Ann.  de  Chim^ 
et  de  Phys.  xxii.  334,  who  adopts  the  opinion  of  Vauquelin  that,  when  puret 
this  acid  does  not  form  purple  salts. 

Erythric  Acid. — A  name  applied  by  Brugnatelli  to  a  substance 
which  he  obtained  by  the  action  of  nitric  on  uric  acid.  Prout  sup- 
poses it  to  be  a  super  salt,  consisting  of  purpuric  and  nitric  acids,  and 
ammonia. — Ann.  of  Phil.  xiv.  363. 

Rosacic  Acid. — A  name  applied  by  Proust  to  a  peculiar  acid  sup- 
posed to  exist  in  the  red  matter,  commonly  called  lateritious  sediment, 
which  is  deposited  in  some  stages  of  fever.  Prout,  however,  con- 
siders it  as  composed  chiefly  of  purpurate  of  ammonia. — Prout  on 
Calculous  diseases.  Vauquelin  and  Vogel,  Ann.  de  Chim.  xciv.  306. 

Amniotic  or  Allantoic  Acid. — Discovered  by  Buniva  and  Vauquelin  in 
the  liquor  of  the  anmios  of  the  cow,  from  which,  by  slow  evaporation, 
it  separates  in  white  crystals.  It  is  very  sparingly  soluble  in  water,  but 
yields  with  the  alkalies,  compounds  which  are  decomposed  by  most  of 
the  acids. — Ann.  de,  Chim.  xxxiii.  279.  Thenard,  Traite  de  Chim.  iv. 
413. 

Lactic  Acid. — A  name  applied  to  a  supposed  distinct  acid,  found  in 
sour  milk,  &c.,  but  which  has  been  proved  to  be  really  the  acetic. — Sec 
a  memoir  on  Digestion  by  Dr.  Prout,  Ann.  of  Phil,  xxviii.  407. 


410  ANTMAL   SUBSTANCES. 

Formic  Acid. — An  acid  extracted  from  ants,  which  in  volatility  and 
odour  resembles  the  acetic,  but  in  composition  is  entirely  different. 
When  sufficiently  cooled  it  becomes  solid,  but  does  not  crystallize ; 
its  specific  gravity  is  1-1168;  it  forms  salts  with  the  oxide  of  copper 
and  other  bases  which  differ  from  the  acetates. — Ann.  of  Phil.  v.  24. 
Dobereiner  has  described  a  process  for  preparing  it  artificially,  Ann.  of 
Phil.  xx.  311.  See  also  Thenard,  iv.  415.  Thomson  on  the  atomic  weight 
of  Formic  Add,  First  Prin.  ii.  149, 

•  Caseic  Acid. — Discovered  in  cheese  by  Proust.  It  is  of  the  colour 
and  consistence  of  syrup ;  reddens  litmus  ;  has  a  bitter  taste  mixed 
with  that  of  cheese  ;  it  concietes  on  standing,  into  a  transparent  mass 
like  honey,  and  it  precipitates  several  metallic  oxides.  Braconnot, 
however,  denies  the  existence  of  this  acid.  [Ann.  de  Chim.  et  de  Phys. 
Oct.  1827.  Henry,  ii.  278.]  Dr.  Thomson  supposes  it  to  be  merely 
'acetic  acid,  disguised  by  a  quantity  of  foreign  matter,  which  retards 
its  volatility. — Inorg.  Chem.  ii.  58. 

Sebacic  Acid. — A  name  applied  by  Thenard  to  an  acid  which  is  ob- 
tained by  the  distillation  of  hog's  lard  or  suet,  and  is  found  in  the  re- 
cipient, mixed  with  acetic  acid,  and  fat  partially  decomposed.  From 
these  it  is  separated  by  boiling  water  and  the  acetate  of  lead  ;  the  re- 
sulting Scbate  of  Lead  is  decomposed  by  sulphuric  acid. — Thenard, 
iv.  420. 

Cholestcric  Acid. — Obtained  by  Pelletier  and  Caventou  from  the 
biliary  concretions,  formed  in  the  human  subject,  by  the  action  of  nitric 
acid.  It  occurs  in  the  form  of  an  orange-yellow  mass  ;  but  when  its 
alcoholic  solution  is  evaporated,  spontaneously,  it  is  deposited  in 
acicular  crystals  of  a  white  colour  ;  it  has  a  styptic  taste,  and  an  odour 
somewhat  like  that  of  butter;  it  is  lighter  than  water,  and  fusible  at 
136J  F. ;  it  reddens  litmus  and  neutralizes  alkalies,  forming  salts  called 
Cholesterates. — Pelletier  and  Caventou,  Jour,  de  Phar.  iii.  292.  Thenard, 
iv.  422. 

Stearic  Acid. — This  acid  is  always  generated  by  the  action  of  alka- 
lies on  the  fat  of  mutton,  beef  or  pork.  It  is  white,  insipid  and  in- 
odorons  ;  it  is  insoluble  in  water,  but  freely  soluble  in  alcohol ;  when 
heated  it  reddens  litmus  ;  it  combines  with  bases  and  forms  a  class  of 
bodies  called  Stearates.  —  Chevreul  sur  les  Corps  Gras.  Thenard,  iv. 
425. 

Margaric  Acid. — An  acid  so  called  by  Chevreul  from  its  pearly  ap- 
pearance ;  it  is  insoluble  in  water,  very  soluble  in  alcohol  and  ether, 
reddens  litmus  and  unites  with  bases,  forming  Margarates.  It  is  ob- 
tained by  putting  soap,  made  of  potassa,  into  water,  and  decomposing 
the  margarate  of  potassa,  which  is  deposited,  with  muriatic  acid. — 
Chevreul.  Thenard,  iv.  430. 

Oleic  Acid — is  thus  named  by  Chevreul  in  consequence  of  its  oily, 
colourless  appearance  ;  it  has  neither  taste  nor  smell ;  continues  fluid 
till  cooled  to  35°,  or,  in  some  varieties,  to  43°  F. ;  is  insoluble  in  wa- 
ter, is  very  soluble  in  alcohol ;  it  combines  with  bases  and  forms  Oleates. 
—-Thenard,  iv.  432. 

The  two  preceding  acids  are  also  formed  during  the  combination  of 
alkalies  with  the  fixed  oils.  [See  page  389.] 

Phocenic  Acid. — A  colourless  liquid  acid,  obtained  by  Chevreul  by  the 
action  of  alkalies  upon  a  peculiar  substance  contained  in  the  oil  of  the 
porpoise,  Delphinum  Phoc&na. — Tkenard}  iv.  435.  It  exists  also  in 


ANIMAL    SUBSTANCES.  411 

gmall  quantities  in  train  oil,  and  in  the  berries  of  the  Viburnum  opulus.— 
Thomson's  Inorg.  Chem.  ii.  130. 

Butyric,  Caproic  and  Capric  Add. — These  acids  are  obtained  by  the 
action  of  an  alkali  upon  Bvtyrine,  a  peculiar  oleaginous  matter  contain- 
ed in  butter. — ChemcuL  Thenard,  iv.  438. 

Hlrcic  Add. — Obtained  by  the  action  of  an  alkali  upon  the  fat  of  the 
goat  and  sheep. — Chevreul. 

Cetic  Add,  is  obtained  by  the  digestion  of  spermaceti  with  pure  po- 
tassa. 

Other  acids  more  or  less  analogous  to  the  preceding  are  formed  du- 
ring the  conversion  of  other  oleaginous  substances  into  soap.  The 
castor  oil  yields  three  acids,  to  which  MM.  Bussy  and  Lecanu  have 
given  the  names  of  Margaritic,  Ricinic  and  Elaiodic  Add.  In  a  simi- 
lar way  Pelletier  and  Caventou  obtained  the  Cevadic  Add  from  the  oil 
derived  from  the  seeds  of  the  Veratrum  sabadilla  and  Jatrophic  or 
Crotonic  from  the  seeds  of  the  croton  tiglium. — Ann.  de  Chim.  et  dt 
Phys.  xiv.  71  Thenard,  iv.  441. 

SECTION  II. 

OLEAGINOUS    SUBSTANCES 

Animal  oils  have  many  properties  in  common  with  those  derived 
from  the  vegetable  kingdom,  and  are  probably  essentially  the  same  ; 
but  both  have  some  peculiarities.  They  are  extensively  employed 
for  giving  light,  and  for  the  manufacture  of  soap.  Their  ultimate  ele- 
ments are  carbon,  hydrogen  and  oxygen  ;  and  most  of  them,  like  the 
fixed  oils,  consist  of  stearine  and  elaine. 

Train  Oil. — Obtained  by  heat  from  the  blubber  of  the  whale,  and 
is  extensively  employed  in  making  oil  gas,  and  for  burning  in  common 
lamps  ;  it  is  of  a  reddish  yellow  colour,  emits  a  strong,  unpleasant 
odour,  and  has  a  considerable  degree  of  viscidity,  which  renders  it 
\infit  for  being  burned  in  Argand's  lamps.  Even  when  purified  it  is 
far  inferior  to  the  spermaceti  oil. — Several  processes  for  depriving  this 
oil  of  its  offensive  odour,  are  described  by  Mr.  Dossie  in  the  Phil.  Mag* 
xv.  and  Chloride  of  Lime  is  proposed  for  the  same  purpose  by  Mr.  David- 
son, Brewster's  Ed.  Jour.  v. 

Spermaceti  oil  is  obtained  from  an  oily  matter  lodged  in  a  bony 
cavity  in  the  head  of  the  Physeter  macrocephalits,  or  spermaceti  whale. 
On  subjecting  this  substance  to  pressure  in  bags,  a  quantity  of  pure 
limpid  oil  is  expressed ;  and  the  residue,  after  being  melted,  strained, 
and  washed  with  a  weak  solution  of  potassa,  is  sold  under  the  name 
of  Spermaceti. 

Spermaceti  is  an  inflammable  substance,  commonly  occurring  in 
crystalline  plates,  of  a  white  colour  and  silvery  lustre ;  it  is  brittle, 
soft  and  slightly  unctuous  to  the  touch  ;  insoluble  in  water,  but  dis- 
solves in  about  thirteen  times  its  weight  of  boiling  alcohol,  and  white 
crystalline  plates  are  deposited  as  the  solution  cools,  to  which  Chev- 
reul  has  given  the  name  of  Celine.  From  this  substance  a  solid  colour- 
less body  has  been  obtained,  denominated  ethal,  which  resembles  ether 
in  it  composition. 

Animal  oil  of  Dippel. — This  name  is  applied  to  a  limpid  volatile 
oil,  which  is  entirely  different  from  the  oils  above  mentioned,  and  is 


412  ANIMAL   SUBSTANCES. 

a  product  of  the  destructive  distillation  of  animal  matter,  especially  of 
albuminous  and  gelatinous  substances.  When  purified  by  distillation, 
it  is  clear  and  transparent.  It  was  formerly  much  used  in  medicine, 
but  is  now  no  longer  employed. 

Hogslard  and  Suet. — The  most  common  kinds  of  fat  are  hogslard 
and  suet,  which  differ  from  each  other  chiefly  in  consistence.  The 
latter,  when  separated  by  fusion  from  the  membrane  in  which  it  oc- 
curs, is  called  tallow,  which  is  extensively  employed  in  the  manufac- 
ture of  soap  and  candles.  Both  these  varieties  of  fat  as  well  as  train 
and  spermaceti  oil,  consist  almost  entirely  of  stearine  and  elaine  ( 
and  when  converted  into  soap  undergo  the  same  change  as  the  fixed 
oils,  yielding  margaric  and  oleic  acids,  and  the  mild  principle  of  oils 
called  Glycerine.  Stearic  acid  is  also  a  constituent  of  soap  made  from 
these  animal  fats. 

Butyrine. — Butter  differs  from  the  common  animal  fats  in  contain- 
ing a  peculiar  oleaginous  matter,  which  is  quite  fluid  at  70°  F.  and  to 
which  M.  Chevreul  has  applied  the  name  of  Butyrine.  When  con* 
verted  into  soap,  it  yields,  in  addition  to  the  usual  products,  three  vo- 
latile odoriferous  compounds,  namely,  the  Butyric,  caproic  and  Capric 
acids. 

Phocenine  is  a  peculiar  fatty  substance  contained  in  the  oil  of  the 
porpoise  (delphinum  phoccma}  mixed  with  elaine.  When  converted  in- 
to soap  it  yields  the  Pkocenic  acid. 

Hircine  is  contained  in  the  fat  of  the  goat  and  sheep,  and  yields  the 
Hircic  acid  when  converted  into  soap. 

Adipocire. — A  name  applied  to  the  fatty  matter  which  remains  when 
a  piece  of  muscle  is  exposed  for  some  time  to  the  action  of  water,  or  in 
kept  in  moist  earth.  According  to  M.  Chevreul,  the  adipocire  is  not 
a  pure  fatty  principle,  but  a  species  of  soap,  chiefly  consisting  of 
margaric  acid,  in  combination  with  ammonia,  generated  during  the  de- 
composition of  the  fibrin.  For  some  curious  facts  concerning  the  for- 
mation of  adipocire,  see  Ures  Cfiem.  Diet. 

Cholesterine. — This  name  is  applied  by  M.  Chevreul  to  the  crystal- 
line matter  which  constitutes  the  basis  of  most  of  the  biliary  concre- 
tions formed  in  the  human  subject.  It  is  a  white  brittle  solid,  of  a 
crystalline  lamellated  structure,  and  brilliant  lustre,  very  much  re 
sembling  spermaceti,  but  it  is  distinguished  from  that  substance  by 
requiring  a  temperature  of  278°  F.  for  fusion,  and  by  not  being  con- 
vertible into  soap  when  digested  in  a  solution  of  potassa  ;  it  is  free 
from  taste  and  odour,  and  is  insoluble  in  water  ;  it  dissolves  freely  in 
boiling  alcohol,  from  which  it  is  deposited  on  cooling  in  white  pearly 
scales ;  when  acted  on  by  concentrated  nitric  acid,  it  is  converted 
into  Cholesteric  acid.  It  has  been  detected  in  the  bile  of  man,  and  of 
several  of  the  lower  animals,  such  as  the  ox,  dog,  pig  and  bear.  The 
best  method  of  preparing  it  is  to  treat  human  biliary  secretions,  re- 
duced to  powder,  with  boiling  alcohol,  and  to  filter  the  hot  solution  as 
rapidly  as  possible.  As  the  solution  cools,  most  of  the  cholesterine 
subsides. — Chevreul — Thcnard,  iv.  506.  Brande's  Jour,  xviii.  403. 

Ambergris. — A  substance  found  floating  on  the  surface  of  the  sea, 
near  the  coasts  of  India,  Africa  and  Brazil,  which  is  supposed  to  be  a 
concretion  formed  in  the  stomach  of  the  spermaceti  whale.  It  has 
been  commonly  regarded  as  a  resinous  principle,  but  its  chief  con- 
stituent is  a  substance  very  analogous  to  cholesterine,  and  to  which 


ANIMAL    SUBSTANCES.   '  413 

Pelletier  and  Caventou  havre  given  the  name  of  Ambreine.  By  di- 
gestion in  nitric  acid,  ambreine  is  converted  into  a  peculiar  acid, 
called  the  Ambreic  acid. — jinn,  of  Phil.  xvi.  93. 


SECTION  III. 


SUBSTANCES    WHTCH    ARE    NEITHER    ACID    NOR    OLEAGINOUS. 

Fibrin  or  Animal  Gluten. — This  substance  forms  the  basis  of  the 
muscular  or  fleshy  parts  of  animals,  and  is  left,  combined  with  albu- 
men, when  all  the  soluble  parts,  consisting  of  gelatine,  osmazome, 
tat,  and  various  salts,  have  been  washed  away  by  hot  water.  It 
may  be  obtained  from  blood,  by  laying  the  coagulum  on  a  linen 
strainer,  and  pouring  water  upon  it  until  a  white  fibrous  matter  re- 
mains ;  or  by  agitating  it  in  a  basin  as  it  flows  from  a  vein,  with  abun- 
dle  of  small  twigs,  which  collect  it  in  a  stringy  form.  Fibrin  is  solid, 
white,  insipid  and  inodorous ;  it  is  heavier  than  water,  and  produces 
no  effect  on  vegetable  colours ;  it  is  soluble  in  the  pure  alkalies,  but 
with  more  difficulty  than  albumen  ;  is  converted  by  acetic  acid  into  a 
tremulous  jelly  which  dissolves  completely  in  warm  water  ;  is  various- 
ly acted  on  by  the  nitric,  sulphuric  and  muriatic  acids. 

REFERENCES.  For  a  full  history  of  the  properties  of  Fibrin,  see  the  Me- 
moir  of  Bcrzelius,  Ann.  de  Chitn.  ixxxviii.  28,  or  Medico-Chirnrgical  Trans. 
iii.  201.  For  BraconnoCs  account  of  Le.ucine,  a  substance  formed  by  the  ac- 
tiott  of  Sulphuric  Acid  on  Fibrin,  nee  Brandos  Jour.  ix.  392.  Thenaru, 
Traile  de  Chim.  iv.  369. 

Albumen. — This  enters  largely  into  the  composition  of  both  animal 
fluids  and  solids.  It  exists  both  in  the  liquid  and  the  solid  form.  Li- 
quid albumen  exists  in  the  serum  of  the  blood,  the  liquor  of  serous  ca- 
vities and  the  fluid  of  the  dropsy.  It  is  best  procured  from  the  white 
of  eggs,  in  which  state  it  is  a  thick  glairy  fluid,  insipid,  and  easily 
miscible  with  cold  water  ;  it  dries  upon  being  exposed  in  thin  layers  to 
the  air,  and  may  then  be  kept,  for  any  length  of  time  without  change; 
it  is  coagulated  by  heat,  alcohol  and  the  stronger  acids  ;  it  is  precipi- 
tated by  several  of  the  metallic  salts,  as  muriate  of  tin,  subacetate  of 
lead,  and  the  muriate  of  gold  ;  it  is  distinguished  from  other  animal 
fluids  by  its  being  coagulated  by  hot  water  ;  its  presence  may  also  be 
detected  by  corrosive  sublimate,  and  by  the  ferrocyanate  of  potassa. — 
For  further  details  concerning  this  substance,  see  Henry,  ii.  416. 

Gelatin,  exists  abundantly  in  the  skin,  cartilages,  tendons,  mem- 
branes and  bones,  but  not  in  healthy  animal  fluids.  Its  distinguishing 
character  is  its  ready  solubility  in  hot  water,  and  the  solution  form- 
ing a  transparent,  tremulous  jelly,  as  it  cools  ;  it  is  insoluble  in  alco- 
hol, but  readily  dissolved  by  most  of  the  diluted  acids  ;  is  also  dis- 
solved by  the  liquid  alkalies,  and  the  solution  is  not  precipitated  by 
acids. 

The  gelatin  of  commerce,  commonly  known  by  the  name  of  Glue, 
is  prepared  by  boiling  in  water  the  cuttings  of  parchment,  or  the 
skins,  ears  and  hoofs  of  animals,  and  evaporating  the  solution.  Isin-. 
glass,  which  is  the  purest  variety  of  gelatin,  is  prepared  from  the 
sounds  of  fish,  of  the  genus  Acipenser,  especially  from  the  sturgeon. 

Bb 


414  ANIMAL   SUBSTANCES. 

The  animal  jelly  of  the  confectioners  is  made  from  the  feet  of  calves, 
the  tendinous  and  ligamentous  parts  of  which  yield  a  large  quantity  of 
gelatin. 

REFERENCES.  Thenard,  Traitede  Chim.  iv.  Hatchett,  on  the  component 
part*  of  Animal  Membrane,  Phil.  Trans.  180i>.  A?i  account  of  the  methods 
of  making  Isinglass,  Glue,  tyc.  may  be  found  in  Johnson's  History  of  Animal 
Chemistry,  i.  311. 

Urea. — This  substance  is  contained  in  urine,  from  which  it  may  be 
obtained  by  slowly  evaporating  the  liquid  to  the  consistence  of  syrup; 
on  cooling,  a  crystalline  mass  is  formed,  from  which  pure  alcohol 
dissolves  urea.  By  the  careful  evaporation  of  the  alcohol  brownish 
crystals  are  deposited,  which  may  be  purified  and  rendered  colourless. 
In  this  state  it  is  soluble  in  water,  especially  when  hot,  and  also  irt 
alcohol  ;  it  is  decomposed  by  the  fixed  alkalies  and  alkaline  earths  ; 
though  not  alkaline  it  unites  with  the  nitric  and  oxalic  acids,  forming 
sparingly  soluble  compounds,  which  crystallize  in  scales  of  a  pearly 
lustre,  and  by  which  the  presence  of  urea  may  be  detected.  This 
substance  has  been  formed  artificially  by  Woiiler. — Brandes  Jour.  N. 
S.  iii.  491.  Front's  process  for  preparing  Urea,  differing  someiohat 
from  the  above,  is  described  in  Henry1  s  and  Turner's  Chemistry. 

Sugar  of  Milk. — The  saccharine  principle  of  milk  is  obtained  by 
evaporating  that  liquid  to  the  consistence  of  syrup,  and  allowing  it  to 
cool.  It  is  afterwards  purified  by  means  of  albumen  and  a  second 
crystallization.  It  has  a  sweet  taste,  though  less  so  than  the  sugar  of 
the  cane,  from  which  also  it  differs  in  several  other  respects. 

Sugar  of  Diabetes. — A  kind  of  sugar  which  may  be  obtained  in  an 
irregularly  crystalline  mass,  by  evaporating  the  urine  voided  in  the  dis- 
ease called  Diabetes. 


SECTION  IV. 

THE  MORE  COMPLEX  ANIMAL  PRODUCTS. 

The  Blood  and  its  Constituents. 

The  blood  while  circulating  in  the  vessels  of  living  animals,  is  fluid, 
of  florid  red  colour  in  the  arteries,  and  of  a  dark  purple  colour  in  the 
veins.  It  has  a  slightly  saline  taste,  and  a  peculiar  odour,  and  is  some- 
what unctuous  to  the  touch  ;  its  specific  gravity  is  variable,  though 
generally  near  1-05,  and  in  man  its  temperature  is  about  98°  or  100° 
F.;  when  fresh  drawn  it  has  the  appearance  of  a  homogeneous  fluid, 
but  if  examined  with  a  microscope  of  sufficient  power,  numerous  red 
particles  are  observed  floating  in  a  colourless  fluid. 

The  blood,  while  circulating,  is  mechanically  distinguishable  into 
two  parts,  one  essentially  liquid,  which  may  be  called  liquor  sanguinis ,- 
the  other  essentially  solid,  which  is  merely  suspended  in  the  former, 
and  imparts  its  red  colour  to  the  mixture.  Both  of  these  constituents 
of  the  blood  are  of  a  complex  nature. 

Liquor  Sanguinis. — This  is  considered  by  some  as  serum,  but  it  has 
been  shown  by  Dr.  B.  Babington  to  be  similar  to  chyle,  and  to  consist 
of  fibrin  held  in  solution,  along  with  albuminous,  oleaginous  and  saline 


ANIMAL   SUBSTANCES.  415 

matter,  by  the  water  of  the  blood.  The  liquor  sanguinis  when  set  at 
rest  coagulates,  and  forms  a  uniform  jelly  of  precisely  the  same  volume 
as  when  it  was  liquid,  and  possesses  the  exact  figure  of  the  contain- 
ing vessel  ;  and  in  a  short  time,  by  the  contraction  of  the  mass  of 
coagulated  fibrin  a  yellowish  liquid  appears,  which  is  the  true  serum  of 
the  blood. 

It  is  the  liquor  sanguinis,  thus  shown  to  be  spontaneously  separable 
into  fibrin  and  serum,  which  forms  a  yellowish  liquid  stratum  at  the 
surface  of  blood  recently  drawn  from  persons  in  acute  rheumatism  or 
other  inflammatory  fevers.  In  such  affections  the  liquor  sanguinis, 
from  causes  not  at  all  understood,  generally  coagulates  with  unusual 
slowness,  so  that  the  heavier  red  globules  have  time  to  subside  to  an 
appreciable  extent,  leaving  an  upper  stratum  of  nearly  colourless  fluid, 
which  by  the  cautious  use  of  a  spoon  may  be  removed  and  collected 
into  a  separate  vessel.  The  bvffy  coat  of  such  blood  is  pure  fibrin  se- 
parated by  coagulation  from  the  liquor  sanguinis.  The  coagulable 
lywpk  of  Surgeons,  which  is  thrown  out  on  cut  surfaces,  appears  to 
be  the  liquor  sanguinis  ;  and  this  fluid  is  also  not  unfrequently  exhaled 
in  dropsies,  when  the  fibrin  either  constitutes  a  gelatinous  deposit,  or 
appears  as  white  flakes  floating  in  a  serous  fluid.  It  is  poured  out  by 
the  intestines  during  an  attack  of  cholera,  the  rice-water  fluid  charac- 
teristic of  that  disease,  consisting  of  a  saline  and  albuminous  solution, 
in  which  numerous  shreds  of  fibrin  are  suspended. — Turner. 

By  allowing  blood  to  remain  exposed  for  a  short  time  to  the  air,  it 
separates  spontaneously  into  two  distinct  portions  : — a  yellowish  li- 
quid called  serum,  and  which  is  identical  with  that  obtained  from  the 
liquor  sanguinis  ;  and  a  red  solid  known  by  the  name  of  clot,  cruor  or 
crassamentum.  The  relative  proportion  of  these  two  parts  is  varia- 
ble, and  depends  upon  circumstances  not  at  all  connected  with  the 
state  of  vigour  and  health  of  the  animal  from  which  the  blood  is 
drawn. 

Serum. — This  liquid  has  a  yellowish  colour,  a  saline  taste  and  slight- 
ly alkaline  reaction  ;  it  is  somewhat  unctuous  to  the  touch,  and  resem- 
bles in  fluidity  warm  olive  oil  ;  its  specific  gravity  is  from  1-027  to 
1-029  ;  it  is  coagulated  by  heat,  and  by  acids,  alcohol  and  other  sub- 
stances that  coagulate  albumen.  When  the  coagulum  prepared  by- 
heat,  is  cut  into  thin  slices  and  subjected  to  pressure,  it  yields  a  small 
quantity  of  a  colourless,  limpid  fluid,  called  serosity — which  contains 
according  to  Dr.  Bostock,  about  l-50th  its  weight  of  animal  matter,  to- 
gether with  a  little  muriate  of  soda. 

The  serum  of  human  blood,  according  to  Berzelius,  consists  in  100 
parts  of  water  90 '59,  albumen  8,  lactate  of  soda  with  animal  matter 
and  chloride  of  sodium  1,  modified  albumen  and  an  alkaline  phosphate 
and  carbonate  0*41. — Traite  de  Chim.  vii.  75. 

Crassamentum  or  Clot. — This  is  the  firm  coagulating  portion  of  the 
blood,  and  has  the  specific  gravity  of  about  1-245.  It  may  be  resolved 
into  two  portions  by  cutting  it  into  thin  slices  and  washing  it  repeated- 
ly in  distilled  water ;  the  colouring  matter,  called  the  red  globules,  is 
gradually  dissolved  or  washed  out,  and  a  white  fibrous  substance  re- 
mains called  fibrin. 

Colouring  matter  of  the  blood.— To  this  substance  the  name  of 
hematosine  is  now  applied.  It  resembles  albumen  in  most  of  its  pro- 
perties, except  in  colour.  Its  elementary  composition  is  nearly  simi- 
lar to  that  of  fibrin  and  albumen,  but  is  differs  from  both,  in  contain- 


416  ANIMAL   SUBSTANCES. 

ing  iron.  This  has  been  satisfactorily  shown  by  Berzelius.  Engelhart 
and  Rose. 

From  the  presence  of  iron  in  the  colouring  matter  of  the  blood, 
some  were  led  to  suppose  that  the  peculiar  colour  of  the  blood  was  in 
some  way  or  other  dependant  upon  that  substance.  But  this  view,  al- 
though supported  by  many  plausible  arguments,  does  not  seem  to  be 
warranted  by  the  facts.  Nor  can  we  at  present  adopt  the  opinion  of 
Mr.  Brande,  that  the  colouring  matter  is  a  peculiar  animal  principle, 
capable  of  combining  with  metallic  oxides. 

With  regard  to  the  colour  of  the  blood,  a  very  interesting  fact  has 
been  stated  by  Dr.  Stevens  in  his  Treatise  on  the  blood,  and  confirmed 
by  Dr.  Turner  and  others  who  have  repeated  the  experiment.  If  per- 
fectly florid  arterial  blood  be  allowed  to  coagulate,  and  the  clot  be 
washed  with  repeated  portions  of  pure  water,  its  colour  gradually  dark- 
ens so  as  at  last  to  appear  quite  black.  Exposure  to  the  air  does  not 
restore  the  colour,  but  a  solution  of  common  salt,  carbonate  of  soda, 
and  other  neutral  salts  restore  it  to  the  original  colour  of  arterial 
blood.  Dr.  Stevens  has  therefore  drawn  the  conclusion,  that  the 
florid  colour  of  arterial  blood  is  not  due  to  oxygen,  but  to  the  sa- 
line matter  of  the  serum. 

Analysis  of  the  Blood. — A  very  elaborate  examination  of  the  blood 
has  been  recently  made  by  Lecanu.  The  following  is  the  mean  of  the 
results  of  two  analyses. 

Water  782-867 

Colouring  matter  126  313 

Albumen  67-252 

Fibrin  2-832 

Saline,  oily,  fatty,  and  extractive  matter  20-736 

1000.000 

Lecanu  has  observed  a  difference  between  the  relative  proportions  of 
the  ingredients  of  the  blood  in  men  and  women  ;  and  this  observation 
has  been  confirmed  by  Dennis,  who  has  made  a  more  extended  exam- 
ination on  this  subject. — Ann.  de  Chim.  xlviii.  308.  Jour,  de  Pharm. 
xvii.  522,  quoted  in  Johnston  s  Report. 

REFERENCES.  Bostock,  in  Medico-Chirurgical  Trans,  ii.  166,  iii.  231; 
and  also  his  work  on  Physiology  Brande,  in  Phil.  Trans.  1812,  and  his 
"Manual  of  Chemistry.  Engelhart,  in  Edin.  Me.d.  and  Surg.  Jour.  Jan.  1827. 
Scudamore  on  the  Blood.  Dr.  J.  Davy's  Observations  on  the  Fibrin,  Biiffy 
Coat,  and  pres  n<e  of  Carbonic  Acid  in  the  Blood,  and  on  the  Heat  given  off 
during  the  coagulation  of  the  Blood,  SfC.  in  Edin.  Med.  and  Surg.  Jour' 
xxix.  244,  xxx.  248,  xxxi.  21.  Berzelius  on  the  presence  of  Iron  in  the  Blood, 
Ann.  de  Chim.  et  de  Pliys.  v.  42,  and  Trails  de  C/tiin.  vii.  60. 

Respiration. — This  function  consists  of  two  distinct  actions,  that  of 
inspiration,  by  which  the  air  is  drawn  into  the  lungs  ;  and  that  of  ex- 
piration, by  which  it  is  expelled  after  having  served  the  purpose  for 
which  it  is  inhaled.  By  an  easy  natural  inspiration,  from  16  to  20 
cubic  inches  may  perhaps,  on  an  average,  be  the  quantity  taken  in  by 
man  of  middle  size.  By  a  forced  expiration,  from  160  to  170  cubic 
inches  may  be  expelled,  after  which  there  still  remain  in  the  lungs 
about  120  cubic  inches,  making  their  entire  contents  about  290  cubic 
inches.  Calculating  from  the  number  of  inspirations  in  24  hours,  and 


ANIMAL   SUBSTANCES.  417 

the  quantity  inspired  at  each,  it  would  appear  that  about  663  cubic 
feet  of  air  are  breathed  during  every  diurnal  period. — Henry,  ii.  460. 

The  air  exhaled  from  the  lungs  is  charged  with  carbonic  acid.  This 
can  be  rendered  manifest  by  breathing  into  lime-water,  which  becomes 
turbid  in  consequence  of  the  formation  of  carbonate  of  lime. 

But  with  regard  to  the  amount  of  this  gaseous  acid  which  is  formed, 
some  difference  of  opinion  exists.  It  was  formerly  supposed  that  it 
was  exactly  equal  to  the  amount  of  oxygen  consumed,  but  more  recent 
researches,  and  especially  those  of  Dulong  and  Despretz,  concur  in 
fixing  the  amount  of  oxygen  consumed  as  greater  than  that  of  the  car- 
bonic acid  formed,  varying  in  different  animals  from  l-10th  to  one  half. 

According  to  Drs.  Front  and  Fyfe,  the  quantity  of  carbonic  acid 
formed  in  the  lungs  is  liable  to  be  materially  affected  m  its  quantity, 
in  the  same  individual,  by  variou>  circumstances.  These  variations 
they  consider  of  two  kinds,  general  or  diurnal,  and  particular. 

It  has  been  generally  supposed  that  the  bulk  of  nitrogen  inhaled 
during  respiration  is  not  changed,  and  that  this  gas  is  merely  passive 
in  the  process,  or  at  least  that  its  only  use  is  to  neutralize  the  ener- 
getic properties  of  the  oxygen.  But  it  has  been  shown  by  that  acuts 
physiologist,  Dr.  Edwards,  that  the  quantity  of  nitrogen  given  out  by 
the  same  animal,  during  respiration,  is  very  variable,  being  at  one  time 
increased,  at  another  diminished,  and  at  a  third  remaining  wholly  un- 
changed. These  phenomena  he  has  traced  to  the  influence  of  the  sea- 
sons. It  has  also  been  shown  by  Allen  and  Pepys,  that  when  animals 
are  confined  in  vessels  of  oxygen  gas,  or  in  an  atmosphere  composed 
of  21  measures  of  oxygen  and  79  of  hydrogen,  the  residual  air  con- 
tains a  large  quantity  of  nitrogen,  and  in  the  latter  case  a  portion  of 
the  hydrogen  has  disappeared.  Dulong  and  Despretz  also,  in  their  ex- 
periments, arrived  at  the  conclusion  that  in  all  cases  there  was  an  in- 
crease of  nitrogen. 

It  appears  therefore  little  doubtful,  that  nitrogen  is  constantly  given 
out  by  the  lungs. 

From  the  experiments  of  Dr.  Edwards  it  appears  to  be  proved,  that 
carbonic  acid  given  out  by  the  lungs,  is  formed  in  the  blood  during  its 
circulation.  For  on  confining  animals  for  some  time  in  an  atmosphere 
of  hydrogen,  the  residual  air  was  found  to  contain  a  quantity  of  car- 
bonic acid,  which  was  in  some  instances  greater  than  the  bulk  of  the 
animal.  It  may  also  be  inferred  from  these  and  other  experiments, 
that  nitrogen  is  absorbed  during  respiration.  And  I  have  elsewhere 
made  the  suggestion,  that  the  nitrogen  thus  absorbed  combines  with 
carbon  and  forms  cyanogen,  which  probably  exists  in  the  blood  in  com- 
bination with  iron. — For  the  facts  and  arguments  in  favour  of  this  view, 
see  Sill.  Jour,  xviii.  52,  and  N.  Y.  Med.  and  Phys.  Jour.  ix.  288. 

REFERENCES.  Bostock's  Physiology.  Edwards  DeV Influence  des  Agents 
Physiques  sur  la  Vie.  Prout  on  the  phenomena  of  Sanguification ,  and  en 
€ie  blood  in  general,  Ann-  de  Phil.  xiii.  12,  265.  The  experiments  of  Allen 
and  Pcpys,  Phil.  Trans.  1808.  Christison's  inquiry  on  some  disputed  points 
in  the  chemical  physiology  of  the  Blood  and  Respiration,  Edin.  Med.  and 
Surg.  Jour.  xxxv.  94.  For  a  good  summary  of  the  various  opinions,  <$•<:• 
see  Henry's  C/iem.  ii.  For  a  full  account  of  the  former  tJieories  and  views  on 
Chis  and  various  other  subjects  relating  to  this  department,  consult  Johnson's 
History  of  Animal  Chemistry,  in  three  vols.  Loud.  1S(!3. 


418  ANIMAL    SUBSTANCES. 

Animal  Heat — The  production  of  animal  heat  appears  to  be  closely 
connected  with  respiration.  A  portion  of  it,  at  least,  can  be  satisfac- 
torily accounted  for  by  the  formation  of  carbonic  acid.  The  remain- 
der has  been  ascribed  to  various  other  sources,  as  the  processes  of  nu- 
trition, secretion,  &c.  Mr.  Brodie,  however,  refers  animal  heat  alto- 
gether to  the  influence  of  the  nervous  system.  But  his  results  have 
not  been  confirmed  by  other  physiologists.  There  is  therefore  much 
obscurity  resting  upon  this  subject. 

REFERENCES.  Crawford  on  Animal  Heat,  Ellis1  Inquiry,  Dr.  J  Davy, 
Phil.  Trans,  for  1814.  The  author  controverts  the  opinion  of  Crawford  as 
to  the  difference  in  the  capacities  of  venous  and  arteiiil  Bltod.  Brodie,  in 
Phil.  Trans.  1811  and  18i2.  He  ascribes  animal  Heat  wholly  to  nervous  in- 
Jluence. 

' 

Animal  Fluids •,  Secretions,  8fc. 

Saliva. — The  saliva  is  the  fluid  secreted  by  the  salivary  glands,  and 
is  poured  into  the  rnouth  during  mastication.  It  is  a  transparent, 
colourless  and  slightly  viscid  fluid,  consisting  of  albumen  and  several 
saline  substances  dissolved  in  water.  From  the  recent  analysis  of 
Tiedemann  and  Grnelin,  the  chief  saline  constituent  is  muriate  of  po- 
tassa  ;  but  several  other  salts,  such  as  the  sulphate,  phosphate,  acetate, 
carbonate,  and  sulphocyanate  of  potassa,  are  likewise  present  in  small 
quantity.  The  concretions  found  in  the  salivary  glands  consist  chieily 
of  carbonate  of  lime. 

REFERENCES.  Bostock9^  Physiology,  containing  the  experiments  of  Tiedt- 
mann  and  Gmelin. 

Pancreatic  Juice. — This  fluid  is  commonly  supposed  to  be  analogous 
to  the  saliva,  but  it  appears  from  the  analysis  of  Tiedemann  and  Gme- 
lin, that  it  is  essentially  different.  The  chief  animal  matters  are  al- 
bumen, and  a  substance  like  curd  ;  but  it  also  contains  a  small  quan- 
tity of  salivary  matter  and  osmazome.  It  reddens  litmus  paper,  owing 
to  the  presence  of  tree  acid,  which  is  supposed  to  be  the  acetic.  Its 
salts  are  nearly  the  same  as  those  contained  in  the  saliva,  except  that 
the  sulphocyanic  acid  is  wanting.  The  uses  of  this  fluid  are  entirely 
unknown. 

Gastric  Juice. — This  is  a  fluid  poured  out  on  the  mucous  coat  of  the 
stomach,  and  appears  to  be  possessed  of  extraordinary  powers  as  a  sol- 
vent. As  collected  from  the  stomach  of  an  animal  killed  while  fast- 
ing, it  is  a  transparent  fluid,  which  has  a  saline  taste,  and  has  neither 
acid  nor  alkaline  reaction  ;  during-  the  process  of  digestion  however,  it 
appears  to  be  distinctly  acid  ;  it  coagulates  milk,  an  effect  which  is 
supposed  to  be  independent  of  the  presence  of  an  acid.  Its  powers 
cannot  be  explained  upon  any  known  chemical  principles. 

REFERENCES.     Prout,  in  Phil.  Trans.  1824.     Bostodc's  Physiology. 

Bile. — The  bile  is  a  yellow  or  greenish-yellow  coloured  fluid,  of  a 
peculiar  sickening  odour,  and  of  a  taste  at  first  sweet  and  then  bitter, 
but  exceedingly  nauseous.  Its  consistence  is  variable,  being  some- 
times limpid,  but  more  commonly  viscid  and  ropy  ;  it  is  rather  denser 
than  water,  and  may  be  mixed  with  that  liquid  in  every  proportion,  it 
contains  a  minute  quantity  of  free  soda,  and  is,  therefore,  slightly  al- 
kaline ;  but  owing  to  the  colour  of  the  bile  itself,  its  action  on  test  pa- 
per is  scarcely  visible. 


ANIMAL    SUBSTANCES.  419 

The  bile,  according  to  the  analysis  of  Tiedemann  and  Gmelin,  is  a- 
very  complex  fluid,  containing,  beside  many  other  ingredients,  a  pe- 
culiar acid,  called  the  Cholic,  which  crystallizes  in  needles,  reddens 
litmus  paper,  and  has  a  sweet  taste. 

The  peculiar  taste  of  the  bile  is  owing  to  a  substance  first  obtained, 
but  not  in  a  pure  state,  by  Thenard,  and  called  by  him  Picromel. 

This  substance,  when  pure,  occurs,  according  to  the  above  named 
chemists,  in  opake  crystalline  grains  ;  soluble  in  water  and  in  alcohol, 
but  not  in  ether  ;  its  taste  is  sweet  without  any  bitterness. 

REFERENCES.  Thenard,  in  Memoirs  U'Arcueil,  i.  or  Traite  de  Cfiim.  \v* 
398  BeizetiuSj  who  denies  the  presence  of  Picromel  in  the  Bile,  Ann.de 
Chim.  Ixxi.  220. 

Biliary  Calculi. — The  concretions  sometimes  found  in  the  human 
gall-bladder,  consist,  according  to  M.  Chevreul,  in  general  of  the  yel- 
low colouring  matter  of  the  bile  and  cholesterine  ;  the  latter  predomi- 
nating and  being  sometimes  in  a  state  of  purity. 

Chyle. — The  fluid  absorbed  by  the  lacteal  vessels  from  the  small  in- 
testines during  the  process  of  digestion,  is  known  by  the  name  of 
Ckylc.  Its  appearance  varies  in  different  animals ;  but  as  collected 
from  the  thoracic  duct  of  a  mammiferous  animal,  three  or  four  hours 
after  a  meal,  it  is  a  white  opake  fluid  like  milk,  having  a  sweetish  and 
slightly  saline  taste.  In  a  few  minutes  after  removal  from  the  duct,  it 
becomes  solid,  and  in  the  course  of  twenty-four  hours  separates  into 
a  firm  coagulum,  and  a  limpid  liquid,  which  may  be  called  the  serum 
of  the  chyle.  The  coagulum  is  an  opake  white  substance,  of  a  slight- 
ly pink  hue,  insoluble  in  water,  but  soluble  easily  in  the  alkalies  and 
alkaline  carbonates.  Vauquelin  regards  it  as  fibrin  in  an  imperfect 
state,  or  as  intermediate  between  that  principle  and  albumen  ;  but  Mr. 
Brande  considers  it  more  closely  allied  to  the  caseous  matter  of  milk 
than  to  fibrin, 

M'dk.  —This  well  known  fluid,  secreted  by  the  females  of  the  class 
mammalia  for  the  nourishment  of  their  young,  consists  of  three  dis- 
tinct parts,  the  cream,  curd,  and  whey,  into  which  by  repose  it  spon- 
taneously separates.  The  cream,  which  collects  upon  its  surface,  is 
an  unctuous,  yellowish- white,  opake  fluid,  of  an  agreeable  flavour. — 
According  to  Berzelius,  100  parts  of  cream  of  specific  gravity  1-0244, 
consist  of  butter  4-5,  caseous  matter  3'5,  and  whey  92.  By  agitation 
as  in  the  process  of  churning,  the  butter  assumes  the  solid  form,  and 
is  thus  obtained  in  a  separate  state.  During  the  operation  there  is  an 
increase  of  temperature  amounting  to  about  three  or  four  degrees, 
oxygen  gas  is  absorbed,  and  an  acid  is  generated  ;  but  the  absorption 
of  oxygen  cannot  be  an  essential  part  of  the  process,  since  butter 
may  be  obtained  by  churning,  even  when  atmospheric  air  is  entirely 
excluded. 

After  the  cream  has  separated  spontaneously,  the  milk  soon  becomes 
sour,  and  gradually  separates  into  a  solid  coagulum,  called  curd,  and  a 
limpid  fluid  which  is  whey.  This  coagulation  is  occasioned  by  free 
acetic  acid,  and  it  may  be  produced  at  pleasure  either  by  adding  a 
free  acid,  or  by  means  of  the  fluid  known  by  the  name  of  renmt, 
which  is  made  by  infusing  the  inner  coat  of  a  calf's  stomach  in  hot 
water.  When  an  acid  is  employed,  the  curd  is  found  to  contain  some 
of  it  in  combination,  and  may,  therefore,  be  regarded  as  an  insoluble 
compound  of  an  acid  with  the  caseous  matter  of  milk  ;  but  nothing 
certain  is  known  respecting  the  mode  by  which  the  gastric  fluid,  the 
active  principle  of  rennet,  produces  its  effect. 


420  ANIMAL    SUBSTANCES. 

The  curd  of  skim-milk,  made  by  means  of  rennet,  and  separated 
from  the  whey  by  washing  with  water,  is  caseous  matter,  or  the  basis 
of  cheese,  in  a  state  of  purity.  It  is  a  white,  insipid,  inodorous  sub- 
stance, insoluble  in  water,  but  readily  soluble  in  the  alkalies,  espe- 
cially in  ammonia.  By  alcohol  it  is  converted,  like  albumen  and 
fibrin,  into  an  adipocirous  substance,  of  a  fetid  odour ;  and,  like  tlie 
same  substance,  it  may  be  dissolved  by  a  sufficient  quantity  of  acetic 
acid. 

REFERENCES.  Braconnot,  Eclin.  Jonr.  of  Science,  viii.  36J>,  denies  the 
accuracy  of  Proust's  observations  concerning  Caseous  Oxide  and  Caseic 
Acid. 

Eggs. — The  shell  of  eggs  is  composed  principally  of  carbonate  of 
lime  with  a  little  animal  matter.  The  white  consists  of  albumen  ;  the 
yolk  consists  principally  of  a  substance  resembling  albumen  and  a 
semi-fluid  oil,  which  may  be  separated  from  the  other  portions  by 
boiling  the  egg.  The  yolk  contains  a  large  quantity  of  phosphorus, 
which  is  obviously  to  supply  phosphoric  aeid  for  forming  the  bones  oi" 
the  chick. 

REFERENCE.     Prouf.  Phil.  Trans.  1822. 

Humours  of  the  Eye. — The  aqueous  and  vitreous  humours  of  the 
eye,  are  composed  principally  of  water,  with  some  saline  matter,  and 
a  trace  of  albumen.  The  crystalline  lens  contains  more  than  half  its 
weight  of  water  and  the  remainder  is  a  peculiar  animal  matter,  very 
analogous  to  albumen,  with  a  trace  of  salts. 

REFERENCE.    Bostock's  Physiology. 

Tears. — The  tears  are  limpid  and  of  a  saline  taste,  dissolve  freely  i« 
water,  and  owing  to  the  presence  of  free  soda,  communicate  a  green 
tint  to  the  blue  infusion  of  violets.  Their  chief  salts  are  the  muriate 
and  phosphate  of  soda.  According  to  Fourcroy  and  Vauquelin,  the 
animal  matter  of  the  tears  is  mucus  ;  but  it  is  more  probably  either 
albumen,  or  some  analogous  principle.  Its  precise  nature  has  not 
however  been  satisfactorily  determined. 

Mucus. — This  term  appears  to  have  been  used  in  very  different  sig- 
nifications. Its  properties  vary  somewhat,  according  to  the  source 
from  which  it  is  derived  ;  but  its  leading  characters  are  in  all  cases 
the  same,  and  are  best  exemplified  in  the  mucus  from  the  nostrils.  It 
appears  to  have  nearly  the  same  composition  as  tears,  but  being  more 
exposed  to  the  air,,  it  suffers  with  more  rapidity  those  changes  caused 
by  the  absorption  of  oxygen,  and  hence  its  greater  viscidness  and  con- 
sistence. 

REFERENCE.  On  the  different  kinds  of  Mucus  t  see  Thenard,  iv.  592. 

Pus. — This  is  the  fluid  secreted  by  an  inflamed  and  ulcerated  sur- 
face. Its  properties  vary  according  to  the  nature  of  the  sore  from 
which  it  is  discharged.  Healthy  pus  is  a  yellowish-white  coloured 
liquid,  of  the  consistence  of  cream,  and  of  a  peculiar  odour  when 
warm  ;  under  the  microscope  it  appears  to  be  composed  of  solid  glo- 
bules, floating  in  a  transparent  fluid  ;  its  specific  gravity  is  about  1*03: 
it  is  insoluble  in  water,  and  is  thickened,  but  not  dissolved  by  alcoho-1; 
it  produces  no  change  on  vegetable  blues,  and  is  dissolved  by  the 
stronger  acids.  It  is  distinguished  from  mucus  according  to  Grassmey- 


ANIMAL    SUBSTANCfc;S.  421 

er,  as  follows  :  triturate  it  with  its  own  weight  of  water,  then  mix  it 
with  an  equal  quantity  of  a  saturated  solution  of  the  carbonate  of  po- 
tassa.  If  it  contain  pus,  a  transparent  jelly  forms  in  a  few  hours  ; 
but  this  does  not  happen  if  mucus  only  is  present. 

REFERENCES.  For  Grassmeyer's  test,  sse  Thomson's  Syst.  iv.  Dr.  Young, 
on  Consumptive  Diseases,  gives  a  test  for  distinguishing  Pus  from  Mucus, 
founded  on  optical  properties.  Sir  E.  Home  on  Ulcers. 

Sweat. — The  excretion  which  is  continually  passing  off  by  the  skin 
in  the  form  of  insensible  perspiration,  consists  chiefly  of  water  ;  but  it 
contains  some  muriate  of  soda  and  free  acetic  acid,  in  consequence 
of  which  it  has  a  saline  taste  and  an  acid  reaction. 

Urine. — Urine  is  an  excretory  fluid  separated  from  the  blood  by  the 
kidneys.  In  its  natural  healthy  state,  it  is  a  transparent,  limpid  fluid, 
of  an  amber  colour,  having  a  saline  taste,  while  warm  emitting  an 
odour  which  is  slightly  aromatic,  and  not  at  all  disagreeable.  Its  spe- 
cific gravity  in  its  most  concentrated  form,  is  about  1-030.  It  gives  a 
red  tint  to  litmus  paper,  a  circumstance  which  indicates  the  presence 
either  of  a  free  acid  or  of  a  super-salt.  Though  at  first  quite  trans- 
parent, an  insoluble  matter  is  deposited  on  standing  ;  so  that  urine, 
voided  at  night,  is  found  to  have  a  light  cloud  floating  in  it  by  the  fol- 
lowing morning.  This  substance  consists  in  part  of  mucus  from  the 
urinary  passages,  and  partly  of  the  superurate  of  ammonia,  which  is 
much  more  soluble  in  warm  than  in  cold  water. 

The  urine  is  yery  prone  to  spontaneous  decomposition.  When  kept 
for  two  or  three  days,  it  acquires  a  strong  urinous  smell ;  and  as  the 
putrefaction  proceeds,  the  disagreeable  odour  increases,  until  at  length 
it  becomes  exceedingly  offensive.  As  soon  as  these  changes  com- 
mence, the  urine  ceases  to  have  an  acid  reaction,  and  the  earthy  phos- 
phates are  deposited.  In  a  short  time,  a  free  alkali  makes  its  appear- 
ance, and  a  large  quantity  of  carbonate  of  ammonia  is  gradually  gen- 
erated. Similar  changes  may  be  produced  in  recent  urine  by  contin- 
ued boiling.  In  both  cases  the  phenomena  are  owing  to  the  decompo- 
sition of  urea,  which  is  almost  entirely  resolved  into  carbonate  of  am- 
monia. 

According  to  the  researches  of  Berzelius,  the  urine  is  one  of  the 
most  complex  animal  fluids,  consisting  of  more  than  twenty  different 
substances.  Of  these,  water  constitutes  933  parts  in  1000  of  urine. 

The  composition  of  the  urine,  however,  is  much  changed  by  the  in- 
fluence of  certain  diseases  :  thus,  sugar  is  found  in  the  urine  voided  in 
diabetes  ;  in  some  cases  of  jaundice  it  is  tinged  of  a  yellow  colour  by 
the  bile  ;  and  in  certain  kinds  of  dropsy,  albumen  is  present  in  it  in 
large  proportion. 

REFERENCES.  For  the  able  researches  of  Berzelius  on  Urine  ^  8pc.  see  his 
general  views  of  the  composition  of  Animal  Fluids,  in  Ann.  of  Phil.  ii.  19, 
195,  377,  415,  and  his  Animal  Chemistry.  Proust,  Ann.  de  Chim.  xxxvi.  258. 
John  on  the  absence  of  Urea  in  Hepatitis,  Aim.  of  Phil.  v.  424,  vi.  392. — 
Prout  on  the  pink  sediment  from  Urine,  Medico  Chir.  Trans,  ix.  481.  Ann. 
of  Phil.  xv.  and  xvi. 

Urinary  Concretions. — The  most  common  kind  of  urinary  concre- 
tions may  be  conveniently  divided  into  the  following  species  :  1.  The 
uric  acid  calculus  ;  2.  The  bone-earth  calculus,  principally  consisting 
of  phosphate  of  lime ;  3.  The  ammoniaco-magnesian  phosphate ; 


422  ANIMAL   SUBSTANCES. 

4.  The  fusible  calculus,  being  a  mixture  of  the  two  preceding  species  ; 

5.  The  mulberry  calculus,  composed  of  oxalate  of  lime  :  6.  The  cystic 
oxide  calculus  ;  7.  The  alternating  calculus  ;  and,  8.  The  compound 
calculus. 

The  Uric  Add  Calculus,  is  a  hard  inodorous  concretion,  commonly 
of  an  oval  form,  of  a  brownish  or  fawn  colour,  and  smooth  surface; 
it  consists  of  layers  arranged  concentrically  around  a  central  nucleus, 
the  laminae  being  distinguished  from  each  other  by  a  slight  difference 
in  colour  ;  it  is  sparingly  soluble  in  water,  and  muriatic  acid  ;  is  solu- 
ble with  effervescence,  by  nitric  acid,  and  the  solution  yields  purpu- 
rate  of  ammonia  when  evaporated  ;  when  digested  in  pure  potassa 
the  acid  is  dissolved  and  the  other  substances  remain ;  before  the 
blow  pipe  it  becomes  black,  emits  a  peculiar  animal  odour,  and  is 
gradually  consumed,  leaving  a  very  small  quantity  of  white  alkaline 
ashes. 

The  Bone-earth  Calculus,  is  of  a  pale  brown  colour,  and  has  a  very 
smooth  surface  ;  it  consists  of  layers,  which  adhere  so  slightly  that 
they  may  be  separated  with  ease  into  concentric  crusts  ;  in  powder, 
it  dissolves  easily  in  dilute  nitric  or  muriatic  acid,  but  is  insoluble  in 
potassa ;  before  the  blow  pipe  it  first  assumes  a  black  colour,  from 
the  decomposition  of  a  little  animal  matter,  and  then  becomes  quite 
white,  undergoing  no  further  changes  unless  the  heat  be  very  intense, 
when  it  is  fused. 

The  Triple  Phosphate  Calculus  rarely  exists  quite  alone,  but  is  gene- 
rally associated  wilh  a  small  proportion  of  phosphate  of  lime.  It  of- 
ten occurs  in  minute  crystals  diffused  over  the  surface,  or  between  the 
interstices  of  other  calculus  larnince  ;  is  generally  white  and  less  com- 
pact than  the  preceding  ;  when  reduced  to  powder  it  is  easily  dissolved 
by  cold  acetic  acid,  and  still  more  easily  by  the  stronger  acids,  the  salt 
being  thrown  down  unchanged  by  ammonia ;  before  the  blow-pipe  a 
smell  of  ammonia  is  given  out,  it  diminishes  in  size,  and  melts  into 
white  pearl  with  rather  more  facility  than  phosphate  of  lime. 

The  Fusible  Calculus  is  recognized  by  the  property  from  which  it 
derives  its  name.  Before  the  blow-pipe  it  froths  and  runs  into  a  glo- 
bule, which  is  either  perfectly  transparent  or  of  a  pearly  whiteness  ;  it 
consists  of  a  mixture  of  the  phosphate  of  lime  and  triple  phosphate  of 
ammonia  and  magnesia. 

The  Mulberry  Calculus  is  named  from  its  resemblance  in  its  rough 
tuberculated  surface,  to  the  fruit  of  the  mulberry.  It  consists  of  oxa- 
late of  lime,  as  was  first  proved  by  Dr.  Wollaston  ;  when  heated  be- 
fore  the  blow-pipe  it  becomes  black,  and  afterwards  white,  and  on  con- 
tinuing the  heat,  a  white  residuum  of  pure  lime  is  obtained,  which 
gives  a  brown  stain  to  moistened  tumeric  paper.  This  calculus  is 
sometimes  smooth,  and  when  mixed  with  uric  acid  becomes  more  re- 
fractory, and  decrepitates  before  the  blow-pipe. 

The  Cystic  Oxide  Calculus,  is  very  rare.  It  resembles  the  triple 
phosphate  calculus,  but  is  more  compact ;  before  the  blow-pipe  it 
emits  a  peculiarly  foetid  smell ;  it  is  readily  soluble  in  almost  all  acids, 
and  in  the  alkalies  ;  is  insoluble  in  alcohol,  water,  acetic,  tartaric  or 
citric  acids,  or  in  solutions  of  neutral  carbonate  of  ammonia;  it  is 
composed  of  animal  matter,  and  it  is  never  accompanied  with  the  mat- 
ter of  any  other  concretion. 

The  Alternating  Calculus,  is  composed  of  alternate  layers  of  two  or 
more  of  the  substances  already  mentioned,  as  constituting  calculi ;  a 


ANIMAL  SUBSTANCES.  423 

fragment  of  each  of  the  layers  may  be  broken  off,  and  its  nature  deter- 
mined by  the  application  of  the  blow-pipe,  and  other  tests  abovemen- 
tioned. 

The  Compound  Calculus,  may  be  known  from  the  equivocal  result8 
presented  when  it  is  subjected  to  chemical  examination ;  it  is  compos- 
ed of  an  intimate  mixture  of  the  ingredients  of  other  calculi. 

Besides  the  calculi  just  mentioned,  three  other  species  have  been  no- 
ticed. Two  of  these  were  described  by  Dr.  Marcet,  under  the  names 
of  Xanthic  Oxide  and  Fibrinous  Calculus,  both  of  which  are  exceedingly 
rare.  The  former  is  of  a  reddish  or  yellow  colour,  is  soluble  in  acids 
and  in  alkalies,  and  its  solution  in  nitric  acid,  when  evaporated,  as- 
sumes a  bright  lemon-yellow  tint ;  the  latter  derives  its  name  from  fi- 
brin, to  which  its  properties  are  closely  analogous.  The  third  species 
consists  chiefly  of  carbonate  of  lime,  and  is  likewise  of  rare  occur- 
rence. 

REFERENCES.  Marcels  Essay  on  the  chemical  history  and  medical  treat- 
ment of  Calcvlous  disorders.  The  papers  of  Dr.  Wallaston  and  Prof. 
Braitde,  in  Phil.  Trans.  1797  and  1810.  Prout's  inquiry  into  the  nature 
and  treatment  of  Gravel,  Calculus,  fyc.  Dr.  Yelloly,  in  Phil.  Trans.  1829. 
Dr.  Henry  on  Urinary  and  other  Morbid  Concretions,  Ann.  of  Phil.  xv.  107. 
See  also  the  ivor/cs  of  Thomson  and  Thenard. 

Solid  Parts  of  Animals. 

Bones. — These  consist  of  earthy  salts  and  animal  matter  intimately 
blended,  the  former  of  which  are  'designed  for  giving  solidity  and  hard- 
ness, arid  the  latter,  for  agglutinating  the  earthy  particles.  The  ani- 
mal substances  are  chiefly  cartillage,  gelatin,  and  a  peculiarly  fatty 
matter  called  marrow. 

According  to  the  analysis  of  Berzelius,  100  parts  of  dry  human 
bones  consist  of  animal  matters  33-3,  phosphate  of  lime  51-04,  car- 
bonate of  lime  11-30,  fluate  of  lime  2,  phosphate  of  magnesia  1  16, 
and  soda,  muriate  of  soda,  and  water  1-2.  Mr.  Hatchett  found,  also, 
a  small  quantity  of  the  sulphate  of  lime  ;  and  Fourcroy  and  Vauquelin 
discovered  traces  of  alumina,  silica,  and  the  oxides  of  iron  and  man- 
ganese, 

REFERENCES.  Processes  for  extracting  Gelatine  from  Bones,  by  D'Arcet, 
and  Gauthier,  Repert.  Arts.  lld  Ser.  xlv.  50.  Repert.  of  Pat.  Invent,  vi.  321. 
On  the  use  of  (he  Gelatine  of  Bones  procured  from  Butcher^1  Meat,  as  an 
Alimentary  Substance,  by  M.  D'Arcet,  Repert.  of  Pat.  Invent,  fyc.  xi.  25. 

Teeth  are  composed  of  the  same  materials  as  bone ;  but  the  enamel 
dissolves  completely  in  dilute  nitric  acid,  and  therefore  is  free  from 
cartilage.  The  composition  of  Ivory  is  similar  to  that  of  the  bony 
matter  of  teeth  in  general. 

The  Shells  of  Eggs  and  the  covering  of  crustaceous  animals,  such 
as  lobsters,  crabs,  and  the  starfish,  consist  of  the  carbonate  and  a  lit- 
tle phosphate  of  lime,  and  animal  matter.  The  shells  of  oysters, 
muscles,  and  other  molluscous  animals  consist  almost  entirely  of  car- 
bonate of  lime  and  animal  matter,  and  the  composition  of  Pearl  and 
Mother  of  Pearl  is  similar. 

Horn  differs  from  bone  in  containing  only  a  trace  of  earth.  It  con- 
sists chiefly  of  gelatin  and  a  cartilaginous  substance  like  coagulated 


424  ANIMAL    SUBSTANCES. 

albumen.  The  composition  of  the  nails  and  hoofs  of  animals  is  simi- 
lar to  that  of  horn  ;  and  the  cuticle  belongs  to  the  same  class  of  sub- 
stances. 

Tendons  appear  to  be  composed  almost  entirely  of  gelatin  ;  for  they 
are  soluble  in  fboiling  water,  and  the  solution  yields  an  abundant  jelly 
on  cooling.  The  composition  of  the  true  skin  is  nearly  the  same  as 
that  of  tendons.  Membranes  and  ligaments  are  composed  chiefly  of 
gelatin,  but  they  also  contain  some  substance  which  is  insoluble  in 
water,  and  is  similar  to  coagulated  albumen. 

In  Hair,  Vauquelin  found  traces  of  silex,  sulphur,  iron  and  manganese 
and  a  peculiar  oil,  which  is  nearly  colourless  in  white  hair,  blackish- 
green  in  dark  hair,  and  red  in  red  hair. 

The  composition  of  Wool  and  Feathers  appears  analogous  to  that  of 
hair.  The  quill  part  of  the  feather  was  found  by  Mr.  Hatchett  to  con* 
gist  of  coagulated  albumen. 

The  flesh  of  animals,  or  Muscle,  consists  essentially  of  fibrin,  but 
independently  of  this  principle,  it  contains  several  other  ingredients, 
such  as  albumen,  gelatin,  a  peculiar  extractive  matter  called  Osma- 
zome,  fat  and  salts  ;  substances  which  are  chiefly  derived  from  the 
blood,  vessels,  and  cellular  membrane,  dispersed  through  the  muscles. 


APPENDIX. 


TABLE  of  the  Atomic  Weights  and  Symbols  of  the  Elementa- 
ry',  and  most  important  Compound,  Bodies. — The  atomic 
weights  are  referred  to  Hydrogen  as  1. 


JV  antes  of 
Subs  lances. 

Symbols- 

At  in.   ||          Pittites  of 
Wts.   I)          Substances. 

Symbols. 

Atom. 

Wts. 

ALUMINUM  i 

Al 

13.7 
25.7 
49.15 
64.6 
76.6 
80.6 
84.6 
117.7 
153.22 
88.6 
96.6 
377 
49.7 
57.7 
53.7 
61.7 
77.7 
68.7 
76.7 
84.7 
104.15 
84.7 
71 
79 
106.45 
87 
8 
78.26 
55.8 
63.8 
91.25 
71.8 
20.5 
28.5 
55.95 
36.5 
36.2 
6 
14 
22 

chloride, 
perchloride, 
hydruret, 
bihydruret, 
bisulphuret, 

C+C1 
2C+3C1 
2C+2H 
C+2H 
C+2S 
Ce 
Ce-fO 
Ce-l-HO 
Cl 

CH-O 

C1+4O 
Cl-i-50 
C1+7O 
Cr 
Cr-f-HO 
Cr-f3O 
Cr-j-HCI 
Cr+3Cl 
Cr+3F 
Co 
Co-fO 
Co-fHO 
Co+Cl 
Co-fS 
Cb 
Cb+2O 
Cb-fSO 
Cu 
2Cu+O 
Cu+O 
Cu+2O 
2Cu+Cl 
Cu+Cl 
2CU+S 
Cu+S 
F 
G 
G+O 
Au 
Au+O 

41.45 
118.55 
14 
8 
38 
46 
54 
58 
35.45 
43.45 
67.45 
75.45 
91.45 
28 
40 
52 
81.22 
134.35 
84.04 
29.5 
37.5 
41.5 
64.95 
45.5 
185 
201 
209 
31.6 
71.2 
39.6 
47.6 
98.65 
67.05 
79.2 
47.6 
18.68 
17.7 
25.7 
200 
208 

oxide,  (alumina) 
chloride, 
ANTIMONY  >  .  .  . 

Al-f-HO 
Al+Cl 
Sb 
Sb+HO 

Sb-j-2O 

oxide, 
deutoxide, 
peroxide, 
sesquichloride, 
perchloride, 
sesquisulphuret, 
bisulphuret, 

Sb+24O 
Sb+l|Cl 
Sb-f-2iCl 
Sb+l4S 
Sb-f2S 
As 
As+UO 
As+2|O 
As+S~ 
As+HS 
As+2iS 
Ba 
Ba+0 
Ba+2O 
Ba+Cl 
Ba+S 
Bi 
Bi+0 
Bi+Cl 
Bi+S 
B 
Br 
Cd 
Cd+O 
Cd-t-Cl 
Cd+S 
Ca 
Ca+O 
Ca-fCl 
Ca-fS 
Ca+P 
C 
C+O 
C+2O 

oxide, 
peroxide, 

protoxide, 
peroxide, 
chloric  acid, 
perchloric  acid, 

[CHROMIUM  .. 

arseriious  acid, 
arsenic  acid, 
sulphuret, 
sesquisulphuret, 
pei  sulphuret, 
BARIUM  

oxide, 
chromic  acid, 
chloride, 
terchloride, 
terfluoride, 

protoxide(baryta) 
peroxide, 
chloride, 
sulphuret, 

oxide, 
peroxide, 
chloride, 
sulphuret, 

oxide, 
chloride, 
sulphuret, 

oxide, 
columbic  acid, 
COPPER  

BROMI'VF              .. 

suboxide,  (red) 
proioxiHf,  (black) 
superoxide, 
subchloride, 
chloride, 
disulphuret, 
sulphuret, 
FLUORINE  

oxide, 
chloride, 
sulphuret, 

oxide,  (lime) 
chloride, 
sulphuret, 
phosphuret, 

GLUCINUM  

oxide  (glucina) 

carbonic  oxide, 
carbonic  acid, 

oxide, 

426 


APPENDIX. 


TABLE    OF    ATOMIC    WEIGHTS    AND    SYMBOLS  —  CONTINUED. 


Names  of 
Substances. 

Symbols.     A$%- 

Names  of         1  «      ,    / 
Substance*         |%™^- 

A.  om 
Wts. 

teroxide, 
chloride, 
terchloride, 
tersulphuret, 

Au-f3O 
Au+Cl 
Au+3Cl 
Au-f3S 
H 
H+O 
H-|-2O 
H-fCl 
H+Br 
H-fl 
H+F 
I 
1+50 
I-T-2C1 
Ir 
Fe 
Fe+0 
Fe-fHO 
Fe+Cl 
Fe+HCl 
Fe+S~ 
Fe-|-2S 
Pb 
Pb+0 
Pb+HO 
Pb+20 
Pb+Cl 
Pb-l-1 
PiH-S 
L 
L+0 
L-I-C1 
L+S 
Mg 
Mg-fO 
Mg+Cl 
Mn 
Mn+O 
Mn+HO 
Mn-f2O 
3Mn-r-40 
4Mn-f70 
Mn-fCl 
2Mn-f-7C! 
Mn-fS 
Hff 
Hg+0 
Hg+20 
Hg+Cl 
Hg-f-2Cl 

Hg+I 
Hg+2I 

Hg+S 
Hff-4-2S 

1224 
235.45 
306.35 
248 
1 
9 
17 
36.45 
79.26 
127 
19.68 
126 
166 
196.90 
98.6 
28 
36 
40 
63.45 
81.22 
44 
60 
103.5 
111.5 
115.5 
119.5 
138.95 
229.5 
119.5 
10 
18 
45.45 
26 
12.7 
20.7 
48.15 
27.7 
35.7 
39.7 
43.7 
115.1 
166.8 
63.15 
303.55 
43.7 
200 
208 
216 
235.45 
270.9 
326 
452 
216 
232 

MOLYBDENUM  

Mo 
Mo-fO 
Mo-f-2O 
Mo-r-2S 
Mo-f3S 
Ni 
Ni+0 
Ni-fHO 
Ni+Cl 
Ni-fS 
N 
N+0 
N+20 
1N-4-3O 
N-f-40 
N-f-50 
N+4C1 
N+31 

N+2C 
O 
Os 
Os+O 
Pd 
Pd+0 
Pd-f2O 
P 

2P+O 
P+HO 

P-f240 

P+HC1 
P+24C1 
P+H" 
P+2H 
Pt 
Pt+O 
PH-2O 
Pt-fCl 
Pt+2Cl 
Pt+S 
Po 

Po+O 
Po-f3O 
Po+Cl 
Po-f-I 
Po-fS 
R 
R-fO 
R+liO 
Se 

47.7 
55.7 
63.7 
79.7 
95.7 
29.5 
37.5 
41.5 
64.9? 
45.5 
14 
22 
30 
38 
46 
54 
155.8 
392 

26 
8 
99 
107 
53 
61 
69 
15.7 

39.4 

27.7 

35.7 

68.87 
104.32 
J6.7? 
17.7 
98.6 
106.6 
114.6 
134.05 
169.5 
114.6 
39.15 

47.15 
63.15 
74.6 
165.15 
55.15 
52 
60 
64 
40 

oxide, 
deutoxide, 
bisulphuret, 
tersulphuret, 

protoxide,  (water 
deutoxide, 
hydrochloric  acid 
hydrobromic  acid 
hvdiiodic  acid, 
hydrofluoric  acid, 

oxide, 
sesquioxide, 
chloride, 
sulphuret, 

protoxide, 
deutoxide, 
hyponitrousacid, 
nitrous  acid, 
nitric  acid, 
chloride, 
iodide, 
bicarburet,  (cya- 
nogen) 

iodic  acid, 
chloriodic  acid, 

IRIDIUM      

oxide, 
peroxide, 
chloride, 
perchloride, 
sulphuret, 
bisulphuret, 

oxide, 
PALI  ADIUM  

oxide, 
sesquioxide, 
peroxide, 
chloride, 
iodide, 
sulphuret, 
LITHIUM   

oxide, 
deutoxide, 
PHOSPHORUS  

hypophosphorous 
acid, 
phosphorous  acid 
phosphoric  acid  ^ 
pyrophosphor-   / 
ic  acid,          ; 
chloride, 
perchloride, 
hydruret, 
bihydruret, 

PL  AT1NUM  

oxide,  (lithia) 
chloride, 
sulphuret, 

oxide,  (magnesia) 
chloride, 

IVTANG  \NESE.  •••  

oxide, 
sesquioxide, 
deutoxide, 
red  oxide, 
varvacite, 
chloride, 
perchloride, 
sulphuret, 

oxide, 
deutoxide, 
chloride, 
bichloride, 
sulphuret, 

protoxide,  (po- 
tassa,  ) 
peroxide, 
chloride, 
iodide, 
sulphuret, 

oxide, 
deutoxide, 
Chloride, 
bichloride, 
iodide, 
deutiodide, 
sulphuret, 
hisulnhuret. 

oxide, 
sesquioxide, 
SELENIUM  

APPENDIX. 


427 


TABLE    OF    ATOMIC    WEIGHTS    AND    SYMBOLS — CONTINUED. 


Names  of 
Substances. 

Symbols. 

Atom. 
Wts. 

1           Names  of 
Substances. 

Symbols,  j 

Atom. 
Wts. 

oxide, 
selenious  acid, 

Se-fO 

Se-j-2O 

48? 
56 

oxide, 
TIN  

Th+0 

St 

67.6 
57  9 

selenic  acid, 

SlLICIUM  

Se-}-30 
Si 

64 

7  5 

oxide, 

deutoxide 

St+O 
gt-j-2O 

65.9 
73  9 

oxide,  (silica) 

Si+0 
Aff 

15.5 

108 

chloride, 
bichloride 

St+Cl 

st-i-2ri 

93.35 

128  8 

oxide, 
chloride, 
iodide, 

Ag+0 
Ag+Cl 

A<r4-I 

116 
143.45 
234 

sulphuret, 
bisulphuret, 
TITANIUM  

st+s 

St-f2S 
Ti 

73.9 
89.9 
24  3 

sulphuret, 

Ag+S 
So 

124 

23  3 

oxide, 
titanic  oxide 

Ti+O 
Ti-j-2O 

32.3 
40  3 

protoxide,  (soda) 
peroxide, 
chloride, 

So-j-O 
So-f-HO 
So+Cl 

31.3 
35.3 

58.75 

bichloride, 
bisulphuret, 

Ti+SCl 
Ti+28 
Tu 

95.2 
56.3 

99  7 

iodide, 
sulphuret, 

So+I 
So+S 
Sr 

149.3 
39.3 
43  8 

oxide, 
timgstic  acid, 
URANIUM 

Tu-t-2O 
Tu+3O 
{T 

115.7 
123.7 
217 

oxide  (strontia) 
chloride, 
iodide, 

Sr+0 
Sr+Cl 
Sr+I 

51.8 
79.25 
169.8 

oxide, 
peroxide, 
VANADIUM  

U+O 

u+uo 
v 

225 
229 
68  5 

sulphuret, 

Sr+S 
g 

59.8 
16 

oxide, 
deutoxide 

v+o 

V-4-2O 

76.5 
84  5 

hyuosulphurous 
acid, 
sulphurous  acid, 
hyposulphuric 
acid, 
sulphuric  acid, 

2S+2O 
S+2O 

2S-f-5O 
S-f3O 

48 
32 

72 

40 

vanadic  acid, 
bichloride, 
terchloride, 
bisulphuret, 
tersulphuret, 

V-1-3O 

V+2C1 
V+3C1 
V-fSS 
V+3S 
y 

92.5 
139.4 

174.85 
100.5 
116.5 
322 

chloride, 
sulphuretted  hy- 

S+C1 

51.45 

oxide,  (yttria) 
ZINC  

Y+O 

Zn 

40.2 
32.5 

drogen, 
TELLURIUM.  

S+H 
Te 

17 
32  2 

oxide, 

Zn+O 

7n  1  PI 

40.5 
67  95 

oxide, 
chloride, 

Te+O 

Te-j-Cl 

40.2 
67.65 

sulphuret, 

Zn+S 

z 

48.5 
30 

bichloride, 
THORIUM..., 

Te+2Cl 
Th 

103.1 
59.6 

oxide,  (zirconia) 

z+o 

38 

428  APPENDIX. 

TABLE  showing  the  Proportions  in  which  several  Gaseous  Bod- 
ies combine  by  Volume.      [From  Dr.  Henry's  Chemistry, ,] 


Names  of  Substances. 

Volumes  of  Elements. 

Resulting 
Volumes. 

Protoxide  of  chlorine,  gas 1  oxygen+2  chlorine 2£ 

Peroxide  of  chlorine,  gas 2  oxygen+1  chlorine 2 

Chloric  acid,  vapour 2£cxygen+l  chlorine 

lodic  acid, 2J  oxygen+1  iodine 

Aqueous  vapour,  steam 1  oxygen+2  hydrogen 2 

Muriatic  acid,  gas 1  chlorine-f-1  hydrogen 2 

Hydriodic  acid,  gas ]  iodine+1  hydrogen 2 

3\itrous  oxide,  gas .....£  oxygen+1  nitrogen 1 

Nitric  oxide,  gas.... 1  oxygen+1  nitrogen 2 

Hyponitrous  acid,  vapour 1£  oxygen-f  1  nitrogen 1 

Nitrous  acid,  vapour 2  oxygen-f  1  nitrogen I 

Nitric  acid,  vapour 2J  oxygen+t  nitrogen i 

Atmospheric  air 1  oxygen+4  nitrogen 5 

Ammonia 3  hydrogen+1  nitrogen 2 

Muriate  of  ammonia 1  muriatic  acid-f  1  ammoriia(solid) 

Sulphurous  acid,  gas 1  oxygen+1  sulphur 1 

Sulphuric  acid,  vapour 1  oxygen-j-2  sulphurous  acid  2 

Sulphuretted  hydrogen,  gas.  ..1  hydrogen-f-1  sulphur 1 

Phosphuretted  hydrogen,  gas..lj  hydrogen+J  phosphorus..! 
Perphosphuretted  hydrogen, gas  1  £  hydrogen+£  phosphorus..!. 

Carbonic  oxide,  gas £  oxygen+1  vapour  of  carbon  1 

Carbonic  acid,  gas 1  oxygen+ivapour  of  carbon  1 

Carbonic  acid £  oxygen-f-1  carbonic  oxide.. .1 

Carbonate  of  ammonia 1  carl),  acid+2  ammonia.. .(solid) 

Sesquicarbonate  of  ammonia. ..1  curb,  aeid+lj  ammonia  (solid) 

Bicarbonate  of  ammonia 1  carb.  acid+1  ammonia. ..(solid) 

Chlorocarbonic  acid,  gas I  carbonic  oxide+1  chlorine  1 

defiant  gas 2  hydrogen+2  carbon I 

Carburetted  hydrogen,  gas 2  hydrogen+1  carbon 1 

Chloric  ether,  vapour .1  chlorine+1  olefiant  gas 

Cyanogen,  gas 1  nitrogen+2  carbon 1 

Chlorocyanic  acid,  vapour 1  chlorine+1  cyanogen 2 

Hydrocyanic  acid,  vapour 1  hydrogen+1  cyanogen 

Sulphuret  of  carbon,  vapour. ..2  sulphur+1  carbon 1 

Alcohol,   vapour 1  olefiant  gas+1  aqueous  vap.l 

Muriatic  ether,  vapour 1  mur.  acid,  gas+2  alcohol. .1 

Sulphurous  ether,  vapour 1  olefiant  gas+1  aqueous  vap.l 


INDEX. 


Acetates,  364, 

Acetous  fermentation,  406. 

Acid  acetic,  363. 

ambreic,  413. 

amniotic  409. 

anthrazothionic,  186. 

antirnonic,  315. 

antimonious,  315. 

arsenic,  299. 

arsenious,  297. 

aspartic,  374. 

auric,  354. 

benzoic,  372. 

boletic,  374. 

boracic,  188. 

bromic,  106. 

butyric,  411. 

caincic,  375. 

camphoric,  374. 

capric.  411. 

caproic,  411. 

carbazotic,  374. 

carbonic,  169. 

caseic  404,  410. 

cetic,  411. 

cevadic,  411. 

chloric,  104. 

chlorous,  103. 

chloriodic.  109. 

chlorocarbonic,  173. 

ehlorochromic,  307. 

chlorocyanic,  182. 

chloroxalic,  375. 

cholesteric,  410. 

cholic,  419. 

chromic,  306. 

citric,  372. 

columbic,  320. 

crameric,  375. 

croconic,  375. 

crotonic,  411, 

cyanic,  182. 

cyanous,  181. 

cyanuric,  181. 

elaiodic,  411. 

ellagic,  374. 

erythric,  409. 


Cc 


Acid)  ferruretted  chyazic,  275. 
ferrocyanic,  274. 
fluoboric,  190. 
fluochromic,  307. 
fluocolumbic,  321. 
fluoric,  121. 
fluosilicic,  262. 
formic,  410. 
fulminic,  182, 
gallic,  373. 
hircic,  411. 
hydriodic,  120. 
hydrobromic,  121. 
hydrochloric,  117. 
hydrocyanic,  184. 
hydrofluoboric,   190. 
hydrofluoric,  121. 
hydroselenic,  193. 
hydrosulphuric,  153. 
hydrothionic,  153. 
hydrothionous,  154. 
hydroxanthic,   187. 
hyponitrous,  131. 
hypophosphorous,  159. 
hyposulphuric,  148. 
hyposulphurous,  145. 
igasuric,  375. 
indigotic,  375, 
iodic,  108 
iodous,  108. 
jathrophic,  411. 
kinic,  375. 
laccic,  376. 
lactic,  409. 
lactucic,  376. 
lampic,  397. 
lithic,  408. 
malic,  372. 
manganeseous,  266. 
manganesic,  266. 
margaric,  389,  410. 
margaritic,  411. 
meconic,  376. 
mellitic,  376. 
molybdic,  304. 
moric,  376. 
moroxylic,  376. 


430 


INDEX. 


Acid,  mucic,  376. 

muriatic,  117. 

nitric,  132. 

nitromuriatic,  135. 

nitrous,  131. 

oleic,  389,  410. 

oxalic,  366. 

oxymuriatic,  100. 

paratartaric,  371. 

pectic.  376. 

perchloric,  104. 

phocenic,  410. 

phosphoric,  159. 

phosphorous,  159. 

prussic,  184. 

purpuric,  409. 

pyroacetic,  365. 

pyrocitric,  372. 

pyrogallic,  374. 

pyroligneous,  364. 

pyromalic,  372. 

pyromucic,  376. 

pyrophosphoric,  159. 

pyrotartaric,  369. 

pyrouric,  409. 

racemic,  371. 

ricinic,  411. 

rosacic,  409. 

saccholactic,  376. 

sebacic,  410, 

selenic,  192. 

selenious,  192. 

silicic,  260. 

silicofluoric,  262. 

sorbic,  372. 

stannic,  285. 

stearic,  410. 

suberic,  377. 

succinic,  377. 

sulphuric,  148. 

sulphurous,  146. 

sulphuretted  chyazic,  186. 

sulphocyanic,  186. 

sulphovinic,  397. 

tartaric,  369. 

tellurous,  324. 

telluric,  325. 

titanic,  323. 

tungstic    312. 

ulmic,  377. 

uric,  408. 

vaierianic.  377. 

vanadic,  310. 

zumie.  377. 
Jdipocire,  412. 


Affinity,  chemical,  22. 
effects  of,  23. 
how  influenced,  24. 
simple,  25. 
elective.  25. 
single  elective,  26. 
double  elective,  26. 
quiescent,  27. 
divellent,  27. 
Air,  atmospheric,  124. 
Albumen,  413. 

vegetable,  404. 
Alcohol,  392. 

in  wine.  393. 
ot  sulphur,  187. 
Mgaroth,  po\vder  of,  314. 
Alkali,  volatile,  137. 
Alkalies,  fixed,  206. 

vegetable,  377. 
Allanite,  321. 
Alloys,  203. 
Mum,  256. 
Alumina,  255. 

salts  of,  256. 
Aluminum,  254. 

oxide  of,  255. 
chloride  of,  255. 
sulphuretof,  256. 
phosphuret  of,  256. 
seleniuret  of,  256. 
Amalgams,  205. 
Amber,  391. 

Ambergris  and  Jlmbrcine,  412. 
Ammonia,  137. 

solution  of,  139. 
acetate  of,  365. 
carbonates  of  171. 
chlorate  of,  140. 
hydriodate  of,  142. 
hydrochl orate  of,  141. 
hydrocyanate  of,  185. 
hydrofluate  of,  142. 
hydrothioriate  of,  156. 
hydrothionite,  156. 
hydrosulphuret  of,  156. 
hypophosphite,  160. 
hyposulphite  of,  155. 
iodate  of,  141. 
muriate  of,  141. 
nitrate  of,  142. 
oxalates  of,  367. 
phosphate  of,  161. 
phosphite  of,  160. 
succinate  of,  377. 
sulphate  of,  155. 


INDEX. 


431 


Ammonia,  sulphite  of,  155. 
Ammoniurets,  200. 
dmidine,  400. 
Amygdaline,  384. 


proximate  &  ultimate,  362. 
Animal  substances,  408. 
gluten,  413. 
heat,  418. 

Anthracite,  165, 399. 
Antimoniates,  315. 
JJntimonites,  315. 
Antimony,  313. 

oxides  of,  314. 
chlorides  of,  315. 
sulphurets  of,  316. 
golden    sulphurets    of 

316 

alloys  of,  317. 
salts  of,  317. 
Aquafortis,  132. 
regia,  135. 
Jlrbor  dianre,  351. 
Archil,  402. 
Arrack,  405. 
Arrow-root,  400. 
Arscniates,  302. 
Arsenic,  296. 

acids  of,  297. 
tests  of,  298. 
chloride  of,  299. 
bromide  of,  299. 
iodide  of,  300. 
hydruret  of,  300. 
sulphurets  of,  300. 
alloys  of,  301. 
Arsenites,  301. 

Arseniuretted  hydrogen,  300. 
Asparagin,  384. 
Asphaltnm,  399. 
Assaying,  197. 
Atmospheric  air,  124. 
Atom,  definition  of,  32. 
Atomic  theory,  31. 

weights  how  ascertained,  32. 
Mropine,  383. 
Attraction,  14. 

remote,  14. 
contiguous,  14. 
cohesive,  14. 
chemical  22. 
heterogeneous,  22. 
Aurates,  354, 
Azote,  123. 


Balance,  torsion,  74. 

Balloons,  111. 

Baldwins,  phosphorus,  247. 

Balsams,  391. 

Barilla,  230. 

Barium,  235. 

oxides  of,  235. 
chloride  of,  236, 
iodide  of,  237. 
sulphuret  of,  237. 
phosphuret  of,  238. 
Barometer,  125. 
Baryta,  or  Barytes,  235. 
hydrate  of,  236. 
salts  of,  238. 
tests  of,  240. 
Bassorin,  384. 
Beer,  405. 
Bell-metal,  332. 
Benzoates,  372. 
Benzule,  373. 

Bile  and  Biliary  calculi,  418. 
Bismuth,  *26. 

oxide  of,  326. 
magistery  of,  328. 
chloride  of,  327. 
sulphu.etof,  327. 
alloys  of,  327. 
salts  of,  328. 
Bitter  principle,  388. 
Bitumen,  398. 
Black-drop,  378. 
Black  dyes,  403. 
lead,  165. 
Bleaching,  100, 

powder,  245. 
Blood,  414. 
Blow-pipe,  common,  64. 

compound,  112. 
Blue,  prussian,  278. 

dyes,  402. 
Boiling-point,  54. 

of  different  liquids,  54. 
varied  by  pressure,  54. 
Bo7ies,  423. 
Borax,  232. 
Boron,  188. 

bichloride  of,  189. 
fluoride  of,  190. 
sulphuret  of,  190. 
Borurets,  metallic,  203. 
Brandy,  405. 
Brass,  332. 
Brazil-wood,  402. 


432 


INDEX. 


Bread,  making  of,  405. 
Brimstojie,  143. 
Bromides,  metallic,  201. 
Bromine,  104. 

chloride  of,  106. 

hydrocarburet  of,  17& 
Bronze,  332. 
Brucine,  381. 

Brunsioick- green,  333,  371* 
Butter,  411,  412. 
Butyrine,  411,  412. 
Buxine,  383. 
Cadmium,  288. 

oxide  of  289. 
chloride  of,  289, 
iodide  of,  289. 
sulphuret  of,  289. 
phosphuret  of,  289. 
alloys  of,  289. 
salts  ofr  289. 
Caffein.  384. 
Catamine,  283. 
Calcium,  243* 

oxides  of,  24?,  244. 

chloride  of,  244. 

iodide  of,  246. 

fluoride  of,  246. 

sulphuret  of,  246. 

phosphuret  of,  246. 
Calculi,  urinary,  422. 
Calomel  342. 
Caloric,  34. 

definition  of,  35. 

nature  of,  35. 

latent,  35,  54 

free,  35. 

of  temperature,  35. 

communication  of,  36. 

radiation  of,  36. 

conduction  of,  40. 

distribution  of,  43. 

equilibrium  of,  43. 

eifects  of,  46. 

expansion  by,  46. 

the  cause  of  fluidity,  52. 

the  cause  of  vapour,  54. 

specific.  59. 

capacity  for,  59. 

sources  of,  60. 
Calorimeter,  59. 
Calx,  198. 
Camphor,  390. 
Camphorates,  374. 
Canton's  phosphorus,  246. 
Caoutchouc,  392. 
Capacity  for  caloric,  59. 


Carbon,  164. 

different  forms  of,  165. 

oxide  of,  168. 

chlorides  of,  171, 

bromide  of,  173. 

iodide  of,  173. 

hydrurets  of,  174. 

hydrochloride  of,  179l 

hydrobromide  of,  179- 

hydriodide  of,  180. 

nitruret  of,  180. 

bisulphuret  of;  187.. 

phosphuret  of,  188. 
Carbonic  acid,  169. 
Carbonic  oxide,  168. 
Carbosulphurcts,  187. 
Carburets,  metallic,  203. 
Carburetted  hydrogen,  174. 
Cartilage,  423. 
Caseous  matter,  419,  420. 
Caseous  oxide,  404. 
Cassius,  purple  of,  355. 
Cathartin,  385. 
Caustic  hmar,  351. 
Cerates,  392. 
Cerin,  392. 
Cerite,  321. 
Cerium,  321. 

oxides  of,  321. 
sulphurets  of,  322s. 
salts  of,  322. 
Cerulin,  402. 
Ceruse,  339. 
Celine,  411. 
Chalk,  249. 

Chameleon,  mineral,  266. 
Charcoal,  165. 

animal,  or  ivory  black 

166. 

Cheese,  420. 
Chemical  affinity  or  attraction,  22, 

equivalents,  28. 

scales  of,  31  u 

Chemistry,  definition  of,  13. 
vegetable,  362. 
animal,  408. 
nomenclature  of,  96i 
Chloric  ether,  398. 
Chlorides,  metallic,  200. 
Chlorme,  100. 

bleaching  powers  of,  100, 

disinfecting    powers    of, 
101. 

fatal  effects  of,  102. 

hydrocarburet  of,  179. 

oxides  of,  102, 103. 


INDEX. 


Chlorine,  cyanide  of,  182. 
C/itonorfzc  acid,  109. 
Chloro- carbonic  acid,  173. 
Chloro -aurates,  354. 
Chloro-hydrar gyrates,  343, 
Chloropkyle,  385. 
Chloro -ptaiinatcs,  357. 
Cholesterine,  412. 
Chromates,  307. 
Chromium}  305. 

oxides  of,  305. 
chloride  of,  307, 
fluoride  of,  307. 
Cinchona  3bark,  active  principle  of, 

380, 

Cinchonine,  380. 
Chyle,  419. 
Cinnabar,  344, 
Citrates,  372, 
Cleavage,  20. 

,  165. 
Z,  399. 
gas,  178, 
,  293. 
oxides  o£  293. 
chloride  of,  294. 
sulphuret  of,  294, 
salts  of,  ^94. 
tests  of,  295. 
Cochineal,  402. 
"Cohesive  attraction,  14. 

influence  of  over  affinitv, 

24. 

Cold,  artificial,  methods  of  produc- 
ing, 53. 

Colocyntin,  385. 
Colouring  matter,  492. 

of  blood,  415. 

Colours,    adjective,  and    substan- 
tive, 402, 
Columbin,  385. 
Columbiunij  320 

oxides  of,  320. 
chloride  of,  321. 
sulphuret  of,  321, 
Combination,  chemical,  27. 

laws,  of  28. 

Combining  proportions,  28. 
Combustion,   62. 
Conductors  of  caloric,  40, 
Conein,  385. 
Congelation,  52. 
Copal,  391. 
Copper,  329. 

oxides  of,  329. 
chlorides  of,  330. 


Copper,  acetates  of,  365. 

sulphurets  of,  331. 
phosphuret  of,  33L 
alloys  of,  33L 
salts  of,  333. 
tests  of,  334 
tinning  of,  332. 
Copperas,  276. 
(Jerk,  388. 
Coirosive  sublimate,  342. 

tests  of,  343. 
Corydaline,  383. 
Coumarin,  390. 
Cream  of  milk,  419, 

tartar,  37& 

Crocus  of  antimony,  317, 
Crotonine,  383. 
Cryophorus,  57, 
Crystallization,  16. 

agents  employed  for,  16. 
circumstances  affecting, 

17. 

water  of,  16, 
Crystals,  primary  forms  of,  19. 

secondary  forms  of,  20. 
Cudbear,  403. 
Cnpellation,  350. 
Curarine,  383, 
Curcuma,  403, 
Curd,  419. 
Cyanogen,  J80. 

chlorides  of,  182,  183, 
bromide  of,  183. 
iodide  of,  384. 
Cyanides,  or  Cyanurets.   metallic, 

203. 

Cyufipine,  383. 
Cystic  oxide,  422. 
Cytisin,  385, 

Daklin,  385. 
Daphnine,  383. 
Daturine,  383. 
Decomposition,  simple,  25» 
double,  26. 
Decrepitation,  16. 
Deflagration,  198. 
Deliquescence.  16. 
Delphme,  383. 
Dew,  Wells'  theory  of,  45. 
Diamond,  164. 
Differential  thermometer,  49» 
Digitaline,  383. 
DippeVs  oil,  411. 
Disinfecting  liquor,  231» 
Dmcm,  385. 


434 


INDEX. 


Dragon's  blood,  391. 
Dyes,  402. 

Earths,  pure,  206. 

alkaline,  206. 
Ebullition,  54. 
Efflorescence,  16. 
Eggs,  420. 
Elaine,  389. 
Elastic,  gum,  392. 
Elective  affinity,  25. 
Electrical  machines,  70v 
Electric  column,  78. 
Electricity,  70. 

facts  of,  70. 

theory  of,   73. 

effects  of,  75. 

atmospheric,  76. 

identical  with  lightning,  76. 

thermo,  95. 

Electro-chemical  theory,  80. 
Electro  -magnetism ,  86. 
Electro -negative  bodies,  96. 
Electro-positive  bodies,  110. 
Electrometers  and  electroscopes,  74. 
Elementary  bodies,  97. 
Emetine,  382. 
Emetic  tartar,  370. 
Emulsion,  389. 
Epsom  salt,  251. 
Equivalents,  chemical,  28. 
scale  of,  3-1. 
Essenbecldne,  384. 
Essential  oils.  390. 
Ethal,  411. 
Ether,  396. 

acetic,  398. 

chloric,  398. 

hydriodic.  398.. 

muriatic.  397. 

nitric,  398. 

phosphoric.  397. 

sulphuric,  396. 
Ethiops,  mineral.  344. : 

per  se,  341. 
Euchlorine,  102. 
Eudiometer,  126. 
Eupatorine*  384. 
Eupion,  387. 
Evaporation,  56. 
Expansion,  of  solids,  46.. 
of  liquids,  47. 
gases,  48. 

Extractive  matter,  388. 
Eyes,  humours  of.  420. 

Fat}  of  animals.  412. 


Feathers,  424. 
Fecula,  400. 
Fermentation,  405. 

acetous,  406. 

panary,  405. 

putrefactive,  406» 

saccharine.  405. 

vinous,  405. 
Ferrocyanates,  277. 
Fibre,  woody,  401. 
Fibrin,  413. 

Fire  damp,  of  coal  mines,  178. 
Fixed  air,  169. 
Fixed  oils,  389. 
Flame,  62. 
Flesh,  424. 

Flowers,  of  benzoin,  372. 
of  sulphur,  143. 
Fluoborates,  190. 
Flaosilicates,  262. 
Fluorine,  110. 
Fluor  spar,  246. 
Flux,  white  and  black,  370. 
Freezing  mixtures,  53. 
Friction,  heat  produced  b}>61. 
Fulminating  gold,  354. 

mercury,  347. 

powder,  218. 

platinum,  358* 

silver,  352. 
Fulminic  acid,  182. 
Fungin,  385. 
Fusion  52. 

watery,  16. 
Fusible  metal,  327. 
Fustic,  403. 

Galena,  337. 

Gallates,  374.  *&  * 

Gall-nuts,  373,  405. 

Gall-stones,  419. 

Galvanic  battery,  77. 

arrangements,  77,  78, 
Galvanism,  77. 

how  developed,  78. 
electrical  agency  of,  79. 
chemical  agency  of,  7& 
igniting  effects  of,  81, 
theory  of,  82. 
Gas,  definition  of,  97. 
exhilerating,  128. 
of  marshes,  175. 
from  coal  and  oil,  177. 
Gastric  juice,  418. 
Gelatin,  413. 
Gems,  artificial,  261. 


INDEX. 


435 


Gentianin,  385. 

Gilding,  356. 

Glass,  of  antimony,  317. 

various  kinds  of,  261. 
Glauber's  salt,  227. 
Gliadine,  404. 
Glucina,  258. 
Glucinum,  257. 

oxide  of,  258. 
Glue,  413. 
Gluten,  404. 
Glycerine,  389,  412. 
GoW,  353. 

oxide  of,  353. 
chlorides  of.  354. 
etherial,  354. 
bromide  of,  355. 
iodide  of,  355. 
sulphuret  of,  355. 
phosphuret  of,  355. 
alloys  of,  355. 
powder,  356. 
fulminating-,  354. 
Gong,  Chinese,  332. 
Goniometers,  21. 
Goulard's  extract,  366. 
Graphite,  165. 

Gravity,  effect  of,   on  chemical  ac- 
tion, 24. 
Gum,  401. 

elastic,  392. 
Gum  resins,  39J. 
Gunpowder,  218. 
Gypsum,  247. 

Hair,  424. 
Hartshorn,  137. 
Heat,  (see  caloric.} 
animal,  418. 
Hematin,  386. 
Hircine,  412. 
Hogslard,  412. 
Hombergs  phosphorus.  244. 
Honey,  400. 
Hoofs,  424. 
Hordein,  400. 
Hydrates,  metallic,  200. 
Hydro,  how  employed,  97. 
Hydrocarbon,  chloride  of,  179. 

bromide  of,  179. 

iodide  of,  180. 
Hydrocyanates,  184. 
Hydrogen,  110. 

deutoxio'e  of,  116. 

protoxide  of,  113. 

arseniuretted,  300. 


Hydrogen,  pliosphuretted,  162. 

carburetted,  174. 

potassiuretted,  212. 

seleniuretted,  193. 

sulphuretted,  153. 

telluretted,  325. 

with  metals,  201. 

carburets  of,  176. 
Hygrometers,  58. 
Hydrosulphurets,  153. 
Hydrurets,  metallic,  201. 
Hyoseyamine,  384. 

Ice,  45,  115 
Imperatorin,  386. 
Incandescence,  69. 
Indigo,  402. 
Ink,  276. 

sympathetic.  294,  328. 

indelible,  351. 
Inulin,  386. 
lodates,  109. 
Iodide  of  nitrogen,  136. 
Iodides,  metallic,  201. 
Iodine,  106. 

and  oxygen,  108. 
arid  sulphur,  152.' 
and  phosphorus.  162. 
bromides  of,  109. 
hydrocarburet  of,  186. 
Ipecacuanha,  382. 

principle  of,  382. 
Iridium,  360. 

oxides  of,  360. 
Iron,  270. 

oxides  of.  270. 

chlorides  of,  272. 

bromides  of,  273. 

iodide  of,  272. 

sulphurets  of,  272. 

phosphuret  of,  272. 

carburets  of,  273. 

cast  and  wrought,  273. 

alloys  of,  274. 

Baits  of,  275. 
Isinglass,  413. 
Isomorphism,  21. 
Ivory  black,  166. 

James1  powder,  317. 
Jelly,  animal,  414. 

Kermes,  mineral,  316. 
Kelp,  230. 
Kreosote,  364. 

Labarraque's  soda  liquid,  231. 


436 


INDEX. 


Lakes,  402. 
Lampblack,  166. 
Lard,  412. 
Latent  heat,  54. 
Lateritious  sediment,  409. 
Laws  of  combination,  28. 
Law  of  multiples,  29. 
Lead,  335. 

oxides  of,  335. 
chloride  of.  336. 
iodide  of,  337. 
sulphuret  of,  337. 
alloys  of.  337. 
salts  of,  338, 
acetate  of,  366. 
tests  of,  339. 
Legumin,  386. 
Lemons,  acid  of,  372. 

.    essential  salt  of,  368. 
Lenses,  61. 
navigation,  15. 
Leyden  jar,  72. 

Libavius,  fuming  liquor  of,  285. 
Ligaments,  424. 
Light,  65. 

laws  of,  66. 
analysis  of,  66. 
illuminating  rays  of,  67. 
heating  rays  of,  67. 
chemical  rays  of,  67. 
magnetic  powers  of,  68. 
sources  of,  69. 
Lightning,  76. 
rod,  76. 
Lignin,  401. 
Lime,  243. 

hydrate  of,  243. 
chloride  of,  245. 
slaked,  244. 
salts  of  247. 
oxalate  of,  369. 
Limestone,  249. 
Linament,  volatile,  389. 
Liquefaction,  52. 
Liquids,  expansion  of  by  heat,  47. 

conducting  power  of,  42. 
Liriodendrine,  386. 
Litharge,  335. 
Uthia,  233. 

salts  of,  234. 
tests  of,  234. 
Lithates,  409. 
Lithium,  233. 

oxide  of,  233. 
chloride  of,  234. 
Litmus,  403. 


Liver  of  antimony,  317. 
J^ogwood,  403. 
Lunar  caustic,  351. 
Lupulin,  386. 

Madarin,  386. 
Madder,  402. 
Magnesia,  250. 

hydrate  of  250. 
calcined,  250. 
salts  of,  251. 
tests  of,  253. 
oxalate  of,  369. 
Magnesium,  249. 

oxide  of,  250 
chloride  of,  250. 
Magnetism,  83. 

laws  of,  83. 
terrestrial,  85. 
electro,  86. 
Malachite,  334. 
Mnlates,  372. 
Maltha,  399. 
Manganese,  264. 

oxides  of,  264. 
chloride  of,  267. 
fluoride  of,  268. 
sulphuret  of,  268. 
phosphuret  of,  268. 
salts  of,  268. 
Manna,  400. 
Marble,  249. 
Massicot,  335. 
Matter,  properties  of,  14. 
Medullin,  386. 
Membranes,  424. 
Menstruum,  22. 
Mercury,  340. 

oxides  of,  341. 
bromides  of,  344. 
chlorides  of,  342. 
iodides  of,  344. 
sulphurets  of  344. 
cyanide  of,  345. 
amalgams  of,  345. 
salts  of,  346. 
fulminating,  347. 
tests  of,  847. 

Metallic  combinations,  203. 
Metals,  195. 

general  properties  of,  195. 
table  of  discovery  of,  195. 
malleability  of.  196. 
ductility  of,  197. 
tenacity  of,  197. 
hardness  of,  197. 


INDEX. 


437 


Metals,  structure  of,  197. 
native  state  of,  197. 
action  of  heat  on,  198. 
action  of  electricity  on,  198. 
and  oxygen,  198. 

water,  200. 

ammonia,  200, 

chlorine,  200. 

bromine,  201. 

iodine,  201. 

fluorine,  201. 

hydrogen,  201.* 

nitrogen,  201. 

sulphur,  201. 

phosphorus,  202. 

carbon,  203. 

cyanogen,  203. 

boron,  203. 

selenium,  203. 

alloys  of,  203. 

amalgams  of,  205. 

classification  of,  206. 
Meteoric  stones,  270,  291. 
Milk,  419. 

sugar  of,  414. 
Minder-erus,  spirit  of,  365. 
Mineral  chamelion,  266. 

caoutchouc,  399. 

pitch,  399. 

tar,  399. 
Minium,  336. 

Mixture,  heat  produced  by,  62. 
Molasses,  400. 
Molybdates,  305. 
Molybdenum,  303. 

oxides  of,  303. 

chlorides  of,  304. 

sulphurets  of,  304. 
Mordant,  402. 
Morphine,  378. 

salts  of,  379. 
Mother  of  Pearl,  423. 
Mucilage,  401. 
Mucus,  420. 
Multiples,  law  of,  29. 
Muriatic  ether,  397. 
Muscle,  424. 
Myricin,  392. 

Nails  of  animals,  424. 
Naphtha,  398. 

from  coal  tar,  177. 
Naphthaline,  177. 
Narcotine,  380. 
Neutral  salt,  97. 
Nickel,  290. 


Nickel,  oxides  of,  291. 
alloys  of,  291. 
salts  of,  292. 
Nicotine,  384. 
Nitre,  217. 

sweet  spirits  of,  « 
Nitrogen,  123. 

oxides  of,  128. 
chloride  of,  135. 
iodide  of,  136. 
Nitrous  acid,  131. 
gas,  129. 
oxide,  128. 
Nomenclature,  96. 


Ot7ofDippel,  411. 

of  vitriol,  149. 

gas,  178. 
Oils,  animal,  411. 

drying,  389. 

fixed,  389. 

vegetable,  389. 

volatile  or  essential,  390. 
Ointment,  392. 
Olefiant  gas,  174. 
Olivile,  386. 
Opium, 

active  principle  of,  378. 
Orpiment,  301. 
Osmazome,  424. 
Osmium,  360. 

oxide  of,  360. 
OxaMes,  367. 
Oxamide,  368. 
Oxide,  cystic,  422. 
Oxide,  xanthic,  423. 
Oxygen,  98. 
Oxijgenized  water,  116. 
Oxy-hydrogen  blow-pipe,  112. 
Oxy-muriatic  acid,  100. 

Packfong,  292. 
Palladium,  359. 

oxide  of,  359. 
Pancreatic  juice,  418. 
Paraffin,  387. 
Patent  yellow,  336. 
Pearls,  423. 
Pearl,  white,  328. 
Pearlash,  221. 
Percussion, 

heat  evolved  by,  61. 
Perspiration,  fluid  of,  417. 
Petroleum,  399. 
Petroline,  399. 
Pewter,  337. 


438 


INDEX. 


Phenicin,  402. 
Phocenine,  412. 
Phosgene  gas,  173. 
Phosphori,  68. 

solar,  68. 

from  heat,  68. 

spontaneous,  68. 
Phosphoric  ether,  397. 
Phosphorus,  156. 

oxide  of,  157. 

chlorides  of,  161. 

bromides  of,  161. 

iodide  of,  162. 

hydrurets  of,  162,  163. 

sulphuret  of,  164. 
Phosphurets,  metallic,  202. 
Phosphur 'cited  hydrogen,  162. 
Photometer,  68. 
Picromel,  419. 
Picrotoxin,  387. 
Pinchbeck,  332. 
Piperin,  387. 
Pitchblende,  318. 
Pitch,  mineral,  399. 
Pit- Coal,  399. 
Plaster  of  Paris,  248. 
Plasters,  389. 
Plating,  350. 
Platinum,  356. 

oxides  of,  357. 

chlorides  of,  357. 

sulphuret  of,  358. 

sulphate  of,  358. 

fulminating,  358. 

alloys  of,  358. 
Plesiomorphism,  21. 
Plumbagin.  387. 
Plumbago,  274. 
Pollenin,  386. 
Polychroite,  387. 
Populin,  387. 
Potassa,  210. 

hydrate  of,  210. 

fusa,  210. 

salts  of,  215. 

acetate  of,  365. 

oxalates  of,  368. 

tartrates  of,  369. 

tests  of,  223. 
Potassa  and  Soda, 

tartrate  of,  370. 

borotartrate  of.  370. 
Potassium  208. 

oxides  of,  210. 

chloride  of,  211. 

bromide  of,  212. 


Potassium,  iodide  of,  212. 

and   hydrogen,  nitrogen, 
sulphur,  phosphorus, 
and  cyanogen,  212. 

alloys  of,  214. 

amalgams  of,  214. 
Potatoe,  starch  of,  401. 
Pot-metal,  337. 
Precipitate,  red,  341. 

white,  343. 
Precipitation,  25. 
Prism,  66. 
Proof  spirit,  393. 
Proportions,  definite,  28. 
combining,  28. 
union  of  bodies  in,  28. 
Proportionals,  28. 
Proximate,  analysis,  362. 

principles,  362. 

of  vegetables,  362. 

of  animal  substances,  403 
Prussian  blue,  278. 
Prussiates,  277. 
Pulverization,  15. 
Purpurates,  409. 
Pus,  420. 
Putrefaction,  406. 
Putrefactive  fermentation,  406. 
Pyrites,  iron,  273. 

copper,  331. 
Pyroxilic  spirit,  365. 
Pyrometers,  51. 

Quantity,  influence  on  affinity,  25. 
Quercitron,  403. 
Quicklime,  244. 
Quicksilver,  340. 
Quinine,  380. 

Radiation,  of  caloric,  36. 
Rays,  luminous,  67. 

calorific,  67. 

chemical,  67. 
Realgar,  300. 
Red  lead,  336. 

dyes,  402. 

precipitate,  341. 
Reduction,  199. 
Rennet,  419. 
Resins,  391. 
Respiration,  416. 
Retinasphaltum,  399. 
Rhodium,  359. 

oxides  of,  360. 
Rhubarbarin,  387. 
Rochelle  salt,  370. 
Rum,  405. 
Saccharine  fermentation,  405. 


INDEX. 


439 


Safety  lamp,  65. 
Safflower,  402. 
Sago,  400. 
Salop,  384. 
Sal-ammoniac,  141. 
Saftcm,  387. 
Salifiabl",  principles,  96 
Salifying  principles,  96. 
Saliva,  418. 
iSfa/J  common,  224. 
of  sorrel,  368. 
petre,  217. 
Salts,  crystallization  of,  16. 

hydrous  and  anhydrous,  16 
Sanguinarine,  382. 
Sarcocoll,  388. 
Saturated  solution,  23. 
Saxon  blue,  402. 
Scale  of  equivalents,  31. 
Scheele's  green,  302. 
Scillitin,  388. 
Secretions,  animal,  418. 
Sealing  wax,  391. 
Selenium,  191. 

oxide  of,  192. 
chloride  of,  193. 
bromide  of,  193. 
sulphuret  of,  194. 
:^.^.    phosphuret  of,  194. 
Seleniurets,  metallic,  203. 
Seleniurettcd,  hydrogen,  193. 
Serocity,  415. 
Serum,  415. 
Shells,  423. 
8jftmg,  15. 
Silica,  or  silex,  260. 
Silicates,  260. 
SUicium,  260. 

oxide  of,  260. 
fluoride  of,  262. 
carburet  of,  262. 
Silver,  348. 

oxides  of,  349. 

chloride  of,  349. 

bromide  of,  349. 

iodide  of,  350. 

sulphuret  and  cyanide  of, 

o50. 

alloys  of,  350. 
salts  of,  351. 
fulminating,  352. 
Smalt,  293. 
Soap,  389. 
Soda,  224. 

hydrate  of,  224. 
salts  of,  226. 


Soda,  tests  of,  233. 

acetate  of,  365. 
Sodmm,  223. 

oxides  of,  224. 
chloride  of,  224.  ^ 
iodide,    sulphuret,    phos-* 

phuret,  226. 
Solanine,  384. 
Solar  rays,  60. 
Solder,  plumber's,  337. 

soft,  328. 
Solution,  22. 
Sorrel,  salt  of,  368. 
Specific  caloric,  59. 
Speculum  metal,  332. 
Spectrum,  solar,  67. 
Spelter,  279, 
Spermaceti,  411. 
Spirit,  proof,  393. 

of  wine,  393. 
Starch,  400. 
Steam,  55. 

engine,  56. 
Stearine,  389. 
Steel,  274. 

alloys  of,  274. 
Strontia,  or  strontites,  240, 
salts  of,  241. 
tests  of,  242. 
Strontium,  240. 

oxides  of,  240. 
chloride  and  iodide  of,241 , 
sulphuret  of,  241. 
Strychnine,  381. 
Suberin,  388. 
Succinates,  377. 
Suet,  412. 
Sublimation,  17. 
Sugar,  399. 

of  lead,  366. 
of  milk,  414. 
of  diabetes,  414. 
!  Sulphocyanates,  186. 
Sulphur,  143. 

crystallization  of.  143, 
milk  of,  144. 
flowers  of,  143. 
arsenic  in,  144. 
chloride  of,  151. 
bromide  of,  152. 
iodide  of,  152. 
cyanide  of,  186. 
alcohol  of,  187. 
Sulphurets,  metallic,  201. 
Sulphuretted  hydrogen,  153. 
Sulphuric  ether,  396. 
Sun,  heat  produced  by  the,  60. 


440 

Supporters,  of  combustion,  96. 
Sweat,  421. 
Synthesis  defined,  98. 
Syrup,  400. 

Tallow,  412. 
Tannin,  natural,  403. 
artificial,  403. 
Tanno  gelatin,  403. 
Tantalite,  320. 
Tantalum,  320. 
Tapioca,  400. 
Tar,  mineral,  399. 
Tartar,  370. 

cream  of,  370. 
emetic,  314,  318,  370. 
soluble,  369. 
Tartrates,  369. 
Tears,  420. 
Teeth,  423. 

Telluretfed,  hydrogen,  325. 
Tellurium,  324. 

oxides  of,  324. 
chlorides  of,  325. 
hydruret  of,  325. 
Temperature,  defined,  35. 
Tenacity  of  metals,  197. 
Tendons,  424. 
Thermo-electricity,  95. 
Thermometers,  49. 
air,  49. 

differential,  49. 
alcohol,  50. 
mercurial,  50. 
register,  52. 
of  contact,  41. 
Thorium  or  thorinum,  263. 

oxide  of,  263. 
Tiglin,  388. 
Tin,  284. 

oxides  of,  284. 
chlorides  of.  285. 
sulphuret  of,  286. 
butter  of,  285. 
alloys  of,  286. 
crystallized,  286. 
salts  of,  287. 
Tin  plate,  286. 
Tincal,  232. 
Titanite,  323. 
Titanium,  322. 

oxides  of,  323. 
chloride  of,  323. 
sulphuret  of,  324. 
Tombac,  332. 
Train-oil,  411. 


INDEX. 


]  Trituration,  15. 
Trona,  231. 
Trough,  galvanic,  77. 
Tungsten,  312. 

oxides  of,  312. 
chlorides  of,  313. 
Turpeth  mineral,  347. 
nitrous,  346. 
Turmeric,  403. 
Turnsol,  403. 
Turpentine,  oil  of,  390. 

spirit  of,  390. 
Type  metal,  317. 

Ulmin,  377. 
Uranium,  318. 

oxide  of,  319. 

salts  of,  319. 
Uran-mica,  320. 
Urates,  409. 
Urea,  414. 
Urine,  421. 
Urinary  calculi,  421. 

Vanadium,  309. 

oxides  of,  310. 
chlorides  of,  311. 
sulphurets  of,  311. 
phosphuret  of,  311. 
Vaporization,  54. 
Vapour,  definition  of,  97. 
latent  heat  of,  55. 
in  the  atmosphere,  126. 
Varnishes,  389. 
Vegetable  substances,  362. 
acids,  363. 
albumen,  404. 
alkalies,  377. 
extract,  388. 
Veratrine,  382. 
Verdigris,  366. 
Verditer,  334. 
Vermilion,  344. 
Vinegar,  distilled,  363. 

formation  of,  406. 
Vinous  fermentation,  405. 
Violine,  384. 
Vitriol,  blue,  333. 
green,  276. 
white,  282. 
oil  of,  149. 
Volatile  alkali,  137. 

linament,  389. 
Voltaic  instruments,  77. 
Volumes,  combinations,  in  30,  428 


INDEX. 


441 


Water,  113. 

properties  of,  113. 

contained  in  the  air,  114. 

combines  with  solids,  L13. 

composition  of,  115. 

expansion  of  in  freezing,  48. 
Wax,  392. 

Welding,  223,  270,  356. 
Wheat,  404. 
Whey,  419. 
Whiskey,  405. 
White  lead,  339. 
Wine,  formation  of,  393. 

alcohol  in,  393., 
Wires,  tenacity  of,  197. 
Woody  fibre,  401. 
Wool,  424. 

Xanthic  oxide,  423. 
Xanthogen,  187. 


Yeast,  404. 

Yellow,  patent  or  mineral,  336. 

kings,  301. 

chrome,  308. 

dyes,  403. 
Yttria,  258. 
Yttrium,  258. 

Znffre,  293. 
Za.nthropicrite,  388. 
Zimome,  404. 
Zinc,  279. 

oxide,   chloride,  iodide  and 
sulphuret  of,  280,  281. 

alloys  of,  282. 

salts  of,  282. 
Zircon,  259. 

tests  of,  260. 
Zirconium,  259. 


ERRATA. 

ge  46,  line  1st  from  top,  for  "  Easy"  read  "  Essay." 

65,  line  17th  from  bottom,  for  "  Chemical  Statistics,"  read  "  Chemica! 
Statics." 

84,  line  14th  from  bottom,  for  "  p.  69,"  read  "  p.  68." 
105,   line  25th  from  bottom,  for  "  lime  springs,"  read"  brine  springs." 
177,  line  I7th  from  top,  for  "  Naphtha  from  Coal  Tar.     And   Naphtha" 

line,"  read  "  Naphtha  from  Coal  Tar  and  Naphthaline." 
189,  line  2d  from  top,  for  "  aad,"  read  "  and." 

195,  line  5th  from  bottom,  for  "  Dr.  \Vallaston,"  read  "  Dr   Wollastoru"' 
197,  line  2d  from  bottom,  for  "  is,"  read  "  are." 
210,  line  1st  from  top,  for  "  Peroxide,"  read  "  Protoxide." 
218,  line  4th  from  top,  for  "  phosphorous,"  read  "  phosphorus." 
226,  line  2d  from  bottom,  for"  Chevenix,"  read  "  Chenevix ." 
223,  line  9th  from  bottom,  for"  Serrulas,"  read  "  Serullas." 
245,  line  18th  from  bottom,  for  "  anylitical,"  read  "  analytical." 
247,  Iine22d  from  top,  for  "  chemica,"  read  "chemical." 
297,  line  14th  from  top,  for  "  Arsenius,"  read  "  Arseriious." 
327,  line  7th  from  top,  for  u  loride,"  read  u  chloride." 
327,   line  12th  from  bottom,  for  "  ane,"  read  "  and  " 
329,  line  3d  from  top,  the  asterisk  should  be  placed  above  "Cu.f* 

331,  line  15th  from  top,  for  "  Bisulphuret,"  read  "  Disulphuret." 

332,  lines  1st  and  8th  from  bottom,  for  »'  Donoran,"  read  "  Donovan.*7 
345,   line 23d  from  top,  for  "  Bycianide,"  read  "  Bieyanide." 

349,  the  Symbol  for  silver  is  sometimes  printed  "  Aq"  instead  of"  \g.n 
368,  line  13th  from  top,  for  "  Binoxolate,"  read  "  Binoxalate." 
377,  line  16th  from  bottom,  for  "  Bracconnet,"read  "  Braconno:." 

393,  Iit»e4th  from  bottom,  for"  Aquoe  vita,"  read  "  Aqua  vi  ae  " 

394,  line  1st,  for  "  Alcohol.     It  can,"  read  "  Alcohol  can." 

395,  line  1st,  in  the  table,  for  "  25-27,"  read  "  25-77." 


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